Title: Subglottal pressure measures during vocal fry phonation
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Title: Subglottal pressure measures during vocal fry phonation
Alternate Title: Vocal fry phonation
Physical Description: vii, 74 leaves : ill. ; 28 cm.
Language: English
Creator: Murry, Thomas, 1943-
Publication Date: 1969
Copyright Date: 1969
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Subject: Speech -- Research   ( lcsh )
Voice   ( lcsh )
Speech thesis Ph. D   ( lcsh )
Dissertations, Academic -- Speech -- UF   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Thesis: Thesis - University of Florida.
Bibliography: Bibliography: leaves 70-74.
Additional Physical Form: Also available on World Wide Web
General Note: Manuscript copy.
General Note: Vita.
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Bibliographic ID: UF00097768
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: alephbibnum - 000559419
oclc - 13489091
notis - ACY4875

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SUBGLOTTAL PRESSURE MEASURES DURING

VOCAL FRY PHONATION















By

THOMAS MURRY


A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY













UNIVERSITY OF FLORIDA










ACKNOWLEDGMENTS


The author expresses sincere gratitude to his com-


mittee chairman Dr. Donald Dew for his continued support

and encouragement during the preparation and execution of

the experiment and also throughout the author's training

program at the University of Florida. Further gratitude is

expressed to the members of the dissertation committee for

their suggestions and contributions to the ideas expressed

herein. Special thanks are given to the subjects who will-

ingly submitted to the procedures of the experiment.

The author wishes to acknowledge the invaluable support


from the faculty, staff, and students of the Communication

Sciences Laboratory and to the staff of the Bronchopulmonary

Laboratory, J. Hillis Miller Health Center. The author is

especially indebted to Mr. Robert Idzikowski for his assis-

tance in preparing the instrumentation for the study, to

Dr. J. O. Harris and Mrs. Joyce Fedik for their assistance


during the experimental sessions, and to Drs. Harry Hollien

and John F. Brandt for their constructive criticism provided

during'the preparation of preliminary drafts of this report.

This research was supported by the National Institutes

of Health grants NB-05475 and NB-06459.














TABLE OF CONTENTS


Page


ACKNOWLEDGMENTS . . . . . . . .


LIST OF TABLES .......


LIST OF FIGURES . . . . . . . .


CHAPTER


1 INTRODUCTION AND STATEMENT OF


II PROCEDURES ....


III RESULTS . .


IV DISCUSSION ....


V SUMMARY AND CONCLUSIONS


APPENDIX A . . .


APPENDIX B . . .


APPENDIX C . . .


APPENDIX D . . .


BIBLIOGRAPHY .....


PROBLEM . .


iii














LIST OF TABLES


Table Page


1 Summary of three-way analysis of
variance to determine the effects
of vowels and phonation conditions
upon the subglottal pressures. .. ... 26


2 Comparison of subglottal pressures
at each phonation condition. The
marginal values contain the sum of
the subglottal pressures for both
vowels at each phonation condition.
The values in the matrix represent
the differences between each marginal
pair . . . . . . ... . 28


3 Summary of three-way analysis of
variance to determine the effects of
the mouthpiece and phonation conditions
upon subglottal pressure .. . 31


4 Comparison of subglottal pressures at
each phonation condition. The marginal
values contain the sum of the subglottal
pressures for both mouthpiece conditions
at each phonation condition. The values
in the matrix represent the differences
between each marginal pair . .. 33


5 Summary of the analysis of variance for
air flow as a function of phonation
conditions ... . . . . . . 36

6 Comparison of the air flow rates at each
phonation condition. The marginal values
in the matrix represent the difference
between each marginal pair. . . 38









7 Phonational ranges for the five subjects
used in the present investigation. The
measures are reported in Hz for the vocal
fry and modal ranges. . .. .. ... 57

8 Mean fundamental frequency, air pressure,
rate of air flow, and relative intensity
for the vowels /a/ and /i/ at five
phonation regions for Subject 1. In con-
ditions 1-10 rate of air flow was not
recorded. . . . . . . . . 64

9 Mean fundamental frequency, air pressure,
rate of air flow, and relative intensity
for the vowels /a/ and /i/ at five phonation
regions for Subject 2. In conditions 1-10
rate of air flow was not recorded. . . 65

10 Mean fundamental frequency, air pressure,
rate of air flow, and relative intensity
for the vowels /a/ and /i/ at five
phonation regions for Subject 3. In con-
ditions 1-10 rate of air flow was not
recorded ... . . ........ . 866

11 Mean fundamental frequency, air pressure,
rate of air flow, and relative intensity
for the vowels /a/ and /i/ at five
phonation regions for Subject 4. In con-
ditions 1-10 rate of air flow was not
recorded. . . .. . . .. 67


12 Mean fundamental frequency, air pressure,
rate of air flow, and relative intensity
for the vowels /a/ and /i/ at five
phonation regions for Subject 5. In con-
ditions 1-10 rate of air flow was not
recorded. ... .. . . . . .. 68


13 Mean fundamental frequency, subglottal
pressure, and rate of air flow at five
phonation conditions for five subjects
producing /a/ and /i/. . . . .. 69


Table


Page














LIST OF FIGURES


Figure Page


1 Block diagram of equipment used to
provide the reference signals, record
the pressure, flow and voice signals,
and monitor subjects' output. . . . 11


2 Subglottal pressure (cm H20) plotted
for the vowels /a/ and /i/ during
three vocal fry and two modal phonation
conditions. . . . .. .. . 24


3 Mean subglottal air pressure (cm H20)
for phonation for /a/ with and without
the air flow recording apparatus in the
mouth at three vocal fry and two modal
phonation conditions. .. . .. .. . 29

4 Air flow rate as a function of phonation
condition. Data points represent means
for five subjects. Combined range of
subjects at each condition indicated by
dotted lines. . .. .. . . . . 34


5 Mean subglottal pressure as a function of
the relative intensity for five subjects
phonating the vowels /a/ and /i/ in vocal
fry. The values for /i/ are underlined . 40

6 Mean subglottal pressure as a function of
the relative intensity for five subjects
phonating the vowel /a/ in vocal fry with
the mouthpiece in place . . . .. 41

7 Mean air flow rate as a function of the
relative intensity for five subjects
phonating the vowel /a/ in vocal fry. . 43










8 Schematic representation of the output
from the Multitrace Oscillograph used
in measuring subglottal pressure and rate
of air flow ... . .. . ... . . . 62















CHAPTER I

INTRODUCTION AND STATEMENT OF PROBLEM



Introduction

Recently, Hollien and Michel (1968) demonstrated that

vocal fry can be appropriately classified as one of the three

frequency ranges used by normal speakers during phonation.

Each of these ranges, falsetto, modal (or mid-range),l and

vocal fry, appears to have distinctive characteristics with

regard to its 1) production, 2) acoustic wave form, and 3)

perceptual attributes. The absolute fundamental frequencies

of the ranges will vary from speaker to speaker, but for any

single speaker, falsetto is produced with the highest funda-

mental frequencies, modal is produced in the middle frequency



The mid-range of the total phonational range is some-
times considered to be the modal register (Morner, Franeson,
and Fant, 1963). As noted by Hollien and Michel (1968), how-
ever, the term "voice register" appears to have no adequate,
accepted definition. In fact, various investigators have
divided the total phonational range into as few as one and as
many as five "voice registers" (Morner, Franeson, and Fant,
1963). It was not the purpose of the research to provide a
description of the term "voice register"; rather, the intent
was to describe certain relationships which occur in vocal
fry, a mode of phonation perceptually described as a quasi
periodic series of relatively distinct pulses.









range, and vocal fry is produced in the lowest range of

fundamental frequencies.

Because vocal fry has been recognized only recently

as a normal phonatory range (Hollien, Moore, Wendahl, and

Michel, 1966) which appears to occur routinely during speech,

it is of particular interest to the scientist. There have

been several investigations concerning the description and

perception of fry (Coleman, 1963; Wendahl, Moore, and Hollien,

1963; Hollien and Michel, 1968; Michel and Hollien, 1968;

Hollien and Wendahl, 1968); information concerning the

operation of the laryngeal structures during vocal fry pho-

nation, however,is somewhat lacking. Specifically, pre-

vious investigations of vocal fry have provided information


concerning the approximate range of vocal fold repetition


rates. For example, in a recent investigation by Hollien

and Michel (1968), the phonational ranges of 12 males and

11 females were found to be from two to 78 pulses per second."


This study confirms the results of earlier investigations


reporting on the approximate range of vocal fry repeti-


tion rates (Michel and Hollien, 1968; McGlone, 1967) and




2When the term, "pulse," is used, it refers to a
function which makes one or more excursions from a base-
line and which has a finite baseline time (Hubbs, 1966).








suggests that fry is characterized by fundamental frequen-

cies lower than those in the modal register.

Hollien and Wendahl (1968)have also reported that

subjects can accurately match the repetition rate of vocal

fry pulse patterns to electronically produced pulses occurring

at low frequencies. Thus, in fry there appears to be suffi-

cient periodicity in the signal for listeners to perceive it

as having low fundamental frequency.

Although low fundamental frequencies are characteris-


tic of vocal fry phonation, Coleman (1963) reported that the

damping of the wave rather than its repetition rate was the

important factor in its perception. Using an electronic


laryngeal analog to vary the damping factor, he reported that

when the damping factor reached a critical value, fry was


always perceived; when the damping factor was less, fry was

not perceived regardless of the frequency. Wendahl, Moore,

and Hollien (1963) have also demonstrated that the vocal fry

acoustic wave forms of human productions show high damping.

Having examined a large number of phonellographic tracings,


they found fry to be characterized by a highly damped wave

form in addition to its low frequency. It appears, therefore,

that vocal fry is a distinct mode of phonation with relatively


low fundamental frequencies and a wave form which is highly

damped.









In an investigation of glottal wave forms, Timke,

Von Leden, and Moore (1958), also provide data which would

support the contention that the vocal fry wave form is highly

damped. Using high speed motion picture photography, they

found the vocal fry glottal wave form to be the result of a

pulse-like opening and closing of the folds followed by a long

closed phase. Indeed, some examples of fry phonation have

been observed (Fant, 1964; Coleman, 1968) which consist of a

double or triple pulse followed by the long closed phase.

Wendahl, Moore, and Hollien (1963) report that while these

patterns were found in their phonellographic tracings, the

most common vocal fold vibratory pattern in vocal fry is one

of a single glottal pulse followed by the characteristically

long closed phase.

Although the production of modal range phonation has


been extensively investigated,the operation of the laryngeal

mechanism during vocal fry has not been specified. This

lack of research may be attributed in part to the miscon-

ception that vocal fry was considered a pathological con-

dition which occurred only infrequently. Clearly, although

vocal fry may be pathological if used extensively, it does

exist as a product of the normal larynx as pointed out pre-

viously. If regarded as a normal phonatory event, then

the mechanism of fry production may be explained within a

framework of other types of normal phonation, namely the








myoelastic-aerodynamic theory of phonation (Van den Berg, 1958).

Investigations of the voice produced during modal pho-

nation have shown frequency to be highly correlated with vocal

fold length,3 mass, and thickness4 and the subglottal pressures

needed to maintain vocal fold movement (Kunze, 1962). While

considerable data have been presented showing the relationship

between vocal fold length and fundamental frequency of pho-

nation in the modal range, it has been shown that the length

of the folds does not appear to vary as a function of the rep-

etition rate in fry (Hollien, Damste, and Murry, 1969).

Investigations of vocal fold thickness (see footnote

four) have generally shown that, as the fundamental frequency

of phonation decreases, the thickness of the vocal folds

increases. Although the reports of the thickness of the vocal

folds during fry as yet are predominantly qualitative, they

indicate that during vocal fry donationn the folds ap-ar to

he rather thick but not necessarily tense. These observations

were noted by Coleman (1968) from examination of high speed

motion pictures, by Hollien, Damste, and Murry (1969)

from a strictly subjective comparison of lateral x-rays



3Irwin, 1940; Brackett, 1947; Sonninen, 1954, 1956;
Hollien, 1960; Hollien and Moore, 1960; Hollien, 1962;
Wendler, 1964; Damste, Hollien, Moore, and Murry, 1968.


4Hollien and Curtis, 1960; Hollien, 1962a, 1962b;
Hollien, Coleman, and Moore, 1968.








and from laminagraphs (Hollien, 1968) taken during modal and

fry phonation.

Most of the data concerning the aerodynamic forces

present during phonation exist for modal range phonation.

Kunze (1962, 1964), Isshiki (1964), and Perkins and Yanagi-

hara (1968) investigated mean rate of air flow over a wide

range of frequencies and found a positive relationship be-

tween air flow rate and intensity. These investigators

found air flow rate to have little or no relationship to

the fundamental frequency of phonation. Additional findings

by Kunze (1962) demonstrated the importance of the air flow

measuring system; he has shown that the absolute values of

flow rates are significantly lower when a respirometer is

used in place of a pneumotachograph.

Air flow rates during sustained phonation of vocal

fry have been obtained by McGlone (1967) using a respirometer.

He found flow rates ranging from 2.0 ml/sec to 71.9 ml/sec

for repetition rates ranging from 10.9 to 52.1 pps. A Pearson

Product-Moment Correlation Coefficient was carried out for

the two sets of measures and found to be .26. These results

for fry phonation, like those obtained for higher frequency

phonation, did not demonstrate any systematic relationship

between air flow rate and repetition rate.

As yet, there are no experimental results of the sub-

glottal pressures produced during vocal fry phonation.









Several investigators have obtained subglottal pressure mea-

sures for low frequency modal phonation of the vowel, /a /

(Van den Berg, 1956; Isshiki, 1959; Ladefoged, 1962; Kunze,

1962); however, their results appear to conflict. For example,

Van den Berg (1956) reported a mean subglottal pressure of

10 cm HI20 for phonation at 145 Hz as compared to 9 cm H20

for phonation at 97 Hz. Isshiki (1959) found an average

pressure of 9 cm H20 for sustained phonation at 123 Hz and


5.5 cm H20 for phonation at 98 Hz. While Ladefoged's (1962)

results show a similar trend, Kunze (1962) noted that as the

subject produced tones below or above the 30 percent point of

his phonational range, subglottal pressure increased. Thus,

the only implication appears to be that frequency increases

as a function of subglottal pressure over the upper portion

of the phonational range. Due to sampling techniques, the use

of a single vowel, and procedural considerations,5 however,


5The measures reported by Ladefoged and his associates
(Draper, Ladefoged, and Whitteridge, 1957, 1959; Ladefoged,
Draper, and Whitteridge, 1958; Ladefoged (1962) are somewhat
higher than those reported by Van den Berg (1956) and Isshiki
(1959). This is, as Kunze (1964) has shown, due to the fact
that Ladefoged's results are based on estimates of subglottal
pressure obtained from recordings of the intraesophageal pres-
sure rather than intratracheal pressure measures. It has been
previously demonstrated (Fry, Stead, Ebert, Lubin, and Wells,
1952; Mead and Whittenberger, 1953) that recordings of intra-
esophageal pressure consist of the intratracheal (airway) pres-
sure which drives the folds plus the pressure required to over-
come the elastic resistance of the lungs. Since this latter
resistance is not constant over the expiratory cycle, it ap-
pears that intraesophageal pressure is not a valid estimate
of subglottal pressure.









this relationship is not clear, especially at the low end of

the modal frequency region.

Kunze's (1962) subglottal pressure measures based

upon recordings of the vowel /a/ by 10 subjects at five points

along their phonational range appear to be the most comprehen-

sive of those reported. He found that from the 90 percent to

10 percent points of the subjects phonational range (excluding


vocal fry), subglottal pressure decreases as the fundamental

frequency decreases except at the subjects' 10 percent point.

In addition, and perhaps of major significance, Kunze demon-

strated the importance of obtaining direct (intratracheal)

measures of subglottal pressures (see footnote five) rather

than indirect estimates of pressure from an esophogeal bal-

loon. He concluded that ". there is little doubt that

intratracheal pressure measures provide the only satisfactory

estimates of subglottal pressure under conditions of sustained

phonation and during connected speech."



Statement of the Problem


Previous studies of the aerodynamic factors contribut-


ing to laryngeal operation have been confined predominantly

to the'middle and upper portions of the phonational range


and have demonstrated that 1) increases in subglottal pres-

sure are usually accompanied by increases in the fundamental

frequency of phonation, 2) subglottal pressure is directly









related to vocal intensity, 3) air flow appears to be re-

lated to vocal intensity, and 4) there is no systematic

relationship between the fundamental frequency of phonation

and air flow rate.

To date, only the variable of air flow rate has been

examined during vocal fry. Specifically, air flow was found

to be significantly lower in vocal fry than in modal phonation

and to have no relationship to fundamental frequency of pho-

nation (McGlone, 1967). In order to understand the operation

of the laryngeal mechanism during vocal fry, it would appear

necessary to examine both air pressure and air flow rate as

they relate to changes in the repetition rate and vocal

intensity of vocal fry phonation.

The major purpose of this study was to determine if

the subglottal pressures and rates of air flow produced dur-

ing vocal fry differ from those in the mid-phonational range.

A second purpose was to investigate the relationship between

the fundamental frequency of phonation of vocal fry and both

subglottal air pressure and rate of air flow. Finally, con-

sideration was given to the observed relationships between

variations in vocal intensity and the subglottal pressure/

air flow data.










CHAPTER II

PROCEDURES


The plan of this study was to obtain simultaneous

measures of the intratracheal air pressure, air flow rate,

and sound pressure during vocal fry and mid-range phonation

from five adult males. These measures were obtained during

sustained phonation of the vowels /a/ and /i/. These vowels

which represent two extreme supraglottal configurations were

chosen to determine if varying the supraglottal structures

affects subglottal pressures. The samples were produced at

three vocal fry and two mid-range fundamental frequencies.1


Equipment


A block diagram of the instrumentation employed in the

present study is shown in Figure 1. While the subject phonat-

ed in a supine position, subglottal pressure was measured di-

rectly through a hypodermic needle inserted between the first

and second tracheal rings, air flow was measured through a

pneumotachograph connected to a mouthpiece held in place by



1In order to avoid considerable confusion in the dis-
cussion of the mode of phonation, the term "fundamental fre-
quency" will be used throughout the remainder of this study
to refer to the quasi periodic laryngeal signal produced
during vocal fry and mid-range phonation. While this term
departs somewhat from standard acoustic terminology (Hubbs,
1966), it appears to be descriptive of the frequency of the
repetitive wave forms found both in vocal fry and mid-range
phonation.






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a flange fitting between the lips and teeth, and sound pres-

sure was measured with a microphone and probe tube inserted

into the connecting tube of the pneumotachograph. Follow-

ing amplification by separate channels of a data amplifier,


each of the three signals was recorded on both an oscillo-

graphic writer and an FM magnetic tape recorder.


For monitoring phonation, the acoustic wave was dis-

played on the face of an oscilloscope in view of the subject

and experimenter and also was presented to each of them by

means of individual earphones. In addition, the subject was


fitted with a second earphone to monitor the frequency of

phonation; the reference signal was generated by a sine-wave

oscillator for mid-range frequencies while a square-wave

generator provided reference signals for vocal fry.



Instrumentation for measuring and calibrating subglottal
pressure

After applying a local anesthetic (one percent xylo-

caine) to the laryngeal area, a physician inserted an 18


gauge hypodermic needle (3.5 inches long with an inside

diameter of .033 inches) between the first and second tracheal


rings so that it was perpendicular to the flow of air through


the trachea. The other end of the needle was connected to a

Statham PM 131 TC differential pressure transducer via a 12 cm

plastic tube having an inside diameter of .125 inches. The









resultant electrical signal was amplified by an Electronics-

for-Medicine DR-8 dc pressure amplifier and recorded simul-

taneously on onechannel of an associated Multitrace Oscillo-

graphic Writer and on one channel of a Honeywell 8100 FM

magnetic tape recorder. Kunze (1964) and Perkins and Yana-

gahara (1968) have shown that direct pressure recordings made

in this manner provide consistent measures of the intratracheal

pressure driving the folds.

The intratracheal pressure measuring system was cali-


brated daily by reference to a U-tube manometer scaled in

centimeters of water (cm H20). The manometer was connected


to the pressure transducer and associated oscillographic

writer by means of a Y-valve having one end open to the atmo-

sphere and the other attached to a syringe. By applying a

steady pressure with the syringe, a specific displacement of

water in the manometer could be calibrated with a specific

pressure change shown on the oscillographic writer. By this

method it was found that the transducer and its system were

linear within the levels needed in the present study.



Instrumentation for measuring air flow


Air flow measurements were made by a pneumotachograph

which operates according to the Law of Poiseuille. That is,

along a rigid tube, there is a decrease in pressure which is

proportional to the velocity of flow per unit length when the










flow is laminar (Rossier, Buhlmann, and Wiesinger, 1954).

Therefore, continuous recording of the pressure diff-

ferences between two points yields a function which,

when integrated, indicates the volume of air moved per

unit of time. In the present study, air flow was recorded


by connecting a Fleish No. 0 pneumotachograph to a mouth-


piece 2.12 inches in length and held in place by a flange


fitting between the lips and teeth. The pneumotachograph


was connected through a Statham PM 97 pressure transducer


to the data amplifier and recording systems. This device,


used with a noseclip, appeared to provide reliable measures


of air flow while avoiding the problems of dead air spaces


and improperly fitting face masks experienced by previous


investigators (Isshiki, 1959; Kunze, 1962; Hardy, 1965).


Calibration of the air flow recording system was


accomplished by passing a known flow rate produced by a


variable speed Emerson RJV-192 vacuum cleaner through a


Fisher-Porter rotameter and to the transducer. The ro-


tameter recorded the flow rate in liters per second; thus,


the deflections on the oscillograph were converted directly


to milliliters of air flow per second (ml/sec).









Sound pressure measurements

Relative intensity levels2 during the vocal fry

conditions were measured by a Brueland Kjaer 4134 one-half

inch condenser microphone with a probe tube six centimeters


long and an inside diameter of .2 mm. The frequency response

of the probe tube and microphone was found to be + 3 dB over


a range of 20-1000 Hz. The microphone probe was fitted into


an insert in the wall of the pneumotachograph and was connect-


ed to its associated Bruel and Kjaer 2801 Microphone Power

Supply. The signal in turn was fed to one channel of the

data recorder, the FM tape recorder, and a Tektronix 310A

oscilloscope. The oscilloscope provided the subject and the

experimenter with a visual trace of the phonation which was


used to maintain constant intensity for each phonation con-

dition.



Monitoring devices


In order to maintain a constant frequency during

phonation, the subject was provided with a reference signal


produced by a General Radio 1313A Oscillator and presented


through a Telephonics TDH 39 earphone, as shown schematically




The intensity levels for the vocal fry conditions
were not predetermined since it was observed in a pilot study
that vocal intensity, measured in front of the mouth tended
to increase as the repetition rate increased.








in Figure 1. The accuracy of the generator was verified by

a Hewlett Packard 5214L Preset Counter. The frequency set-

tings were determined from the information obtained from

the subjects' phonational ranges (Appendix A). The vocal fry

reference signals were square waves set at slow, medium, and

fast frequencies of the subject's fry phonational range. The

reference signals for the 10 and 30 percent frequencies of

the modal range were sine waves set at the predetermined fre-


quencies for each subject.



Experimental Procedure


Subje cts


Five adult males were selected for the investigation.

The subjects volunteered to perform the tasks and were chosen

on the basis of the following criteria: 1) they were capable


of phonating in vocal fry over a range of repetition rates;

and 2) they showed no evidence or history of voice disorders

or laryngeal pathology.

Phonational ranges

Prior to the experimental task, each subject's modal

and vocal fry phonational ranges were determined. The modal

range was obtained in the traditional fashion by having


each subject sing up and down the musical scale until he

produced his highest and then his lowest sustainable notes.

In order to monitor his production, he was instructed to match









a series of pure tones presented at tone interval's. The

subject and the experimenter acted as judges to determine

which tones represented the extremes of his modal range.

The highest and lowest frequencies produced by the subject

and agreed upon by the experimenter were considered as the

modal phonational range boundaries.

The vocal fry range was determined by a procedure

similar to that described by Hollien and Michel (1968).

Specifically, each subject practiced producing vocal fry

at various repetition rates, then varied the rates upward

and downward until reaching the lowest and highest sustainable

repetition rate. When the experimenter and subject agreed

upon these limits, a four-second sample was recorded on

magnetic tape. To measure repetition rate, tape loops of

the samples were played through a General Radio 1900A Wave

Analyzer coupled to a Hewlett Packard 5214L Preset Counter.


The wave analyzer was set to the tracking generator mode

having a three-cycle bandwidth. When the largest deflection

appeared on the voltmeter, the frequency at that point was

recorded from the counter. The mid and fry phonational ranges

of all subjects are shown and discussed in Appendix A.

Tasks

After administering a local anesthetic to the laryngeal

area, a physician inserted the hypodermic needle for recording

the intratracheal pressure. The needle was connected to the









transducer and the subject was given ample time to adjust

to the experimental apparatus. Each subject was then in-

structed to produce three samples of the vowels /a/ and /i/

at slow, medium, and fast repetition rates within his vocal

fry phonational range as well as at his 10 and 30 percent

points of the modal range. Subsequently, the mouthpiece

leading from the pneumotachograph was fitted and the subject

was asked to produce samples of the vowel /a/ at the three

vocal fry and two modal range frequencies. All recordings

were made while the subject was in the supine position. A

set of earphones presented the reference signal at one ear

while the subject monitored his vocal output at the other ear.

Thus, in the first series of recordings, subglottal pressure

was recorded during phonation of two vowels at five frequencies.

In the second series, subglottal air pressure and air flow were

recorded for the vowel /a/ only at the five frequency con-

ditions since it appeared that recordings of /i/ would be

greatly distorted in phonemic quality or would result in air

leakage around the mouthpiece. Appendix B contains the re-

cording itinerary followed throughout.



Data Analysis

For each subject, frequency and pressure recordings

were made for the vowels /a/ and /i/ at three frequency re-

gions in vocal fry and two in the modal range. During a









separate recording period, the frequency, pressure, and air

flow were obtained for the vowel /a/ only at five frequency

regions. It was necessary to convert the outputs of the

multitrace oscillographic writer into numerical values (Appen-

dixC) to estimate the actual subglottal pressure and rate


of air flow. This was accomplished by measuring the pressure

shifts produced on the oscillographic writer at 100 milli-

second intervals for three seconds and converting the values

to centimeters of water for subglottal air pressure and milli-

liters of air per second for air flow using the appropriate

calibration factors previously obtained. For each phonation

a mean and standard deviation was computed. The means of three

samples at a particular phonation condition were computed for

frequency, subglottal air pressure, rate of air flow, and


relative intensity3 and used as the criterion measures.


The fundamental frequency data were obtained from the

Honeywell FM tape recorder. The recorder was slowed by a


factor of eight and played through a Sanborn 150-1300D Dynagraph.



3The relative intensity levels were obtained by record-
ing a two-volt sine wave on the tape recorder and playing it
back through a Bruel and Kjaer 2112 Audio Frequency Spectrometer
which acted as an attenuater. The output or the spectrometer
was coupled to a Bruel and Kjaer 2305 Graphic Level Recorder
which recorded the reference signal at mid-scale with a 50 dB
potentiometer. The measures reported arerelative to this scale
value rather than to the actual 2-volt signal. The use of the
scale values eliminates the large negative dB values.









Wave-to-wave measurements of the output of each sample were

made by measuring the wave from peak-to-peak, dividing this

by eight times the speed of the dynagraph to get the period.

1
Using the formula F = period measures were converted to


frequency in Hz.


Two analyses of variance with repeated measures were

performed on the subglottal pressure measures to determine

the effects of vowels, the mouthpiece, and the frequency of

phonation on the subglottal pressures (Lindquist, 1953). The

first was a frequency-by-vowel-by-subject anaylsis to determine

the effects of the phonation condition and vowel. The second

tested the effects of phonation condition and addition of the

mouthpiece on subglottal pressure. Since only one vowel was

used during the pressure and flow recordings, a one-way analysis


of variance with repeated measures was performed on the air flow

data to determine the effects of frequency changes on air flow

rate. Thus, it was possible to test differences in pressure

for effects due to frequency, vowel, and insertion of the

mouthpiece and in air flow for effects due to frequency of

phonation.

To determine the relationship between the actual


repetition rate and subglottal pressure during vocal fry

phonation, a Pearson Product-Moment Correlation Coefficient

was computed for the variables of repetition rate and subglottal





21



pressure. Similarly, a Pearson Product-Moment Correlation

Coefficient was computed between repetition rate in vocal

fry and rate of air flow.
















CHAPTER III

RESULTS



The major purpose of this study was to determine if

the subglottal pressures and rates of air flow produced

during vocal fry phonation differ from those produced in

modal range phonation. This study also investigated the

relationships of both subglottal air pressure and rate of

air flow with a) fundamental frequency and b) vocal intensity.


In order to accomplish these purposes, simultaneous recordings

of the intratracheal air pressure, air flow, and sound pres-

sure were obtained from five subjects phonating the vowels

/a/ and /i/ at five fundamental frequency regions, three in

the vocal fry and two in the modal range. Three samples at


each experimental condition were obtained; the criterion

measures were the mean frequency, mean subglottal pressure,


mean rate of air flow, and average relative intensity for

three samples in each condition.


It should be noted that the subglottal air pressures


and mean rates of air flow obtained in the present study


varied from subject to subject as well as between successive

samples produced by the same subject. For example, subject











two was found to have mean subglottal air pressures which

were higher than those of most other subjects; however,

the frequencies at which he was phonating were similar to

the other.subjects. Moreover, examination of the raw data

showed that subject two had little sample-to-sample varia-

tion in comparison to subject one. The reader should be

aware of the existence of the variability found in this as

well as other investigations (Kunze, 1962) when interpret-

ing the present data.



Subglottal Pressure During Vocal Fry

Relationship of subglottal pressure to phonation condition
and vowel


The mean subglottal pressures for the vowels /a/ and

/i/ produced at three vocal fry and two modal frequency

regions of the subjects' ranges are shown in Figure 2.

Figure 2 clearly indicates that the subjects' subglottal

air pressure was greater in vocal fry than in the two modal

range conditions. Moreover, there were no reversals in this

trend at any phonation condition. From Figure 2 it can also

be seen that as subjects increased frequency of phonation

in vocal fry, the subglottal pressure increased. In the


modal range conditions, however, the subglottal pressures

decreased as the subjects' frequency increased from the 10 percent

















S/Ia/ O /I/


MEDIUM
VOCAL FRY


FAST


10%
10%


MODAL
PHONATION CONDITION


Figure 2. Subglottal pressure (cm H20) plotted for the
vowels /a/ and /i/ during three vocal fry and two modal
phonation conditions.


JIO
10
E
9



0-









4
-J 7

0,
t-


. 4




3


SLOW


30%









region1 of their modal phonational range. In vocal fry, the

overall mean increase in subglottal pressure from the slow

repetition rates to the fast rates was statistically signif-

icant at the five percent level. In view of the variability

exhibited by the subjects during the production of the modal

range frequencies, however it can only be shown that as the

subjects increased their fundamental frequency, subglottal

pressures decreased significantly as the fundamental frequency

approached the 30 percent region of a subject's modal pho-

national range.


Figure 2 also shows that the subglottal pressure trends

which were found for the /a/ were similar to those found for


/i/; although the values for /i/ were higher in all but one

condition, the differences were not significant.


To determine if the changes in subglottal pressure as

a function of the five phonation conditions (i.e., slow, me-

dium, and fast fry, and 10 and 30 percent modal), and vowels

were statistically significant, a treatments by treatments by

subjects analysis of variance (Lindquist, 1953) was performed.

The results of this analysis are presented in Table 1. The


effect of phonation condition was significant at the .05 level;




While all subjects did not produce all samples at the
exact 10 and 30 percent frequencies of their modal phonational
range, the means of the three samples were within three semi-
tones of the desired frequency.

















Table 1. Summary of three-way analysis of variance to
determine the effects of vowels and phonation conditions
upon the subglottal pressures.




Source of Variation SS df MS F




A Phonation condition 125.38 4 31.35 4.52*
B Vowels 4.33 1 4.33 1.56
S Subjects 81.47 4 20.37
AB 1.95 4 .49 .53
AS 110.51 16 6.91
BS 11.08 4 2.77
ABS 14.67 16 .92


Total 349.39 49


*Significant at
(F = 3.01, F
.05,4,16 .05,


the .05 level
=7.71).
1,4


of confidence









the effects due to vowels and the AB interaction were not


statistically significant at the tested level.

To determine which of the phonation conditions


accounted for the overall significance of this effect, the

Newman-Keuls test of treatment differences following an


overall significant F-ratio was applied to the data. This

statistic tests the difference between any number of means


arranged in increasing order of magnitude while maintaining

the level of significance equal to alpha. The results of

this test presented in Table 2 indicate that all phonation

conditions were significantly different from each other.

That is, the pressures in all samples of vocal fry were


significantly greater than the pressures in all samples of


mid-range phonation. Furthermore, the matrix shows that


the pressures at the 10 percent modal frequency were sig-

nificantly greater than those at the 30 percent region and

also that the pressures at each of the three fry frequency

regions were significantly different from each other.



Effects of mouthpiece and phonation condition upon subglottal
pressure


As described previously, subglottal pressures for the

vowel /a/ were recorded when the subject had a mouthpiece in-

serted for the purpose of recording air flow rate and when


the mouthpiece was not inserted. Figure 3 presents the























*0








0 41
I








00
C0.0
o o0









40 > i












0-4
H 0





amo















0


O 0 cn
0 30










0- 0V
0) 1















0
H-F m .
M .H











>00











0 o -r
0.00.0
>~ it d i




^ ^ +*
ri 3 r
6-1 S I .


S0CO 0


0 0 C 0







* 4
Nr-1



o 0 l














(0C








0l C (





























CO
0 0 (0 0



0 0 C lI
0OCU
0- *

CO.HCI2

























































SLOW


I I
MEDIUM FAST
VOCAL FRY

PHONATION


/ / WITHOUT
MOUTHPIECE



Sa/ WITH
MOUTHPIECE


10%
MODAL

CONDITION


30
30%


-Mean subglottal air pressure (cm H20) for
for /a/ with and without the air flow recording
in the mouth at three vocal fry and two modal
conditions.


10 1-


0






-j
<, 6

F-
0
( 5
V)

.I


Figure 3.
phonation
apparatus
phonation









results for the mean subglottal pressures for the /a/ under

these two conditions plotted as a function of phonation

condition. Figure 3 indicates that the subglottal pressures

for both treatment conditions, i.e., with and without the

mouthpiece, increased as a function of the phonation con-

dition in vocal fry. The subglotta] pressures in the modal

range were lower than those in vocal fry and tended to de-

crease as the subjects increased frequency of phonation.

When the subglottal pressures for the two recording condi-

tions are compared at any one phonation condition, it can

be seen that the pressures produced while the subject was

fitted with the mouthpeice were lower than when the mouth-


piece was removed. Thus, it appears that the addition of

the mouthpiece for recording air flow rate caused a reduction

in the subglottal pressures.

An analysis of variance was performed to determine if

the changes in pressure as a function of the two variables

was statistically significant; Table 3 summarizes this anal-

ysis. The effects due to insertion of the mouthpiece were

not significant at the .05 level. The effects due to pho-

nation condition were significant at the .05 level; the AB

interaction was not significant at the tested level.

The Newman-Keuls test was applied to the data to de-

termine which of the phonation conditions accounted for the


















Table 3. Summary of three-way analysis of variance to
determine the effects of the mouthpiece and phonation
conditions upon subglottal pressure.



Source of Variation SS df MS F




A Phonation condition 99.73 4 24.93 7.16*
B Mouthpiece 8.00 1 8.00 1.04
S Subjects 96.00 4 24.00
AB 3.69 4 .92 .52
AS 55.79 16 3.48
BS 30.63 4 7.66
ABS 28.08 16 1.76


*Significant at the .05 level
(F 05,4 16= 3.01, F 7.71).
.05, 1,4


of confidence









overall significance of this effect. Table 4 presents the

results of this test. It can be seen that all fry pressures

were significantly different from those in the modal range.

The pressures within each range, however, were not statis-

tically significant from each other at the .05 level.

Thus, it was found that subglottal pressure during

vocal fry is greater than during modal range phonation. It

was also found that subglottal pressure increases as a func-

tion of frequency in vocal fry over the range of frequencies

produced by the five subjects in this experiment. Subglottal

pressure decreased from the 10 to 30 percent frequencies in

the modal range. Furthermore, the pressures produced during

phonation of /i/ in the vocal fry and modal frequency ranges

are greater than the pressures produced during phonation of


/a/; however, this difference was not statistically signifi-

cant. Finally, the insertion of a mouthpiece for recording

air flow rate has no statistically significant effect upon

the pressures produced while phonating /a/; however, the

pressures produced under this condition are less than when

the mouthpiece is not in place.



Air flow rate and mode of phonation


Mean rate of air flow was obtained during phonation of

/a/ at the five phonation conditions. The results of these

measures are shown in Figure 4. In Figure 4, mean rate of





















* *
0000
0 W 4 0
' N 4 1-
n C i- i-


0 0 a)


00
E-4



4' +,
A C
,cd








00



0jc


0-.4 0











+) 0


0)4
0 o
E 0
0 0)







CO
O -fl0












0 0
oH 4

















41
0 0








E' 0
43En
Ol 0












.00)0
04 0



M C






0-HO



mOH-
SC-V





HOC
^ bd Q

0 CJ


000
C ,- 0
N Ho

m 4














200-



180-



160-
I--r

I
160- I I
I I

I I
140 -
VI



0
E 120-



uL 100
T T

u-
0 80-



S60 I



40-

20 i I I
I I !
20 I ..
L I


I I I I I
SLOW MEDIUM FAST 10% 30%
VOCAL FRY RANGE MODAL RANGE

PHONATION CONDITION

Fi gure 4. Air flow rate as a function of phonation condition.
Data points represent means for five subjects. Combined range
of subjects at each condition indicated by dotted lines.









air flow is plotted as a function of the three vocal fry

and two modal range frequencies of phonation. The extended

lines from the data points indicate the range of air flow

rates at that condition for the combined group of subjects.

From Figure 4, it is apparent that the mean air flow rate

during vocal fry phonation is lower than during modal range

phonation. While there appears to be an increaseof flow rate

as frequency increases, the ranges obtained from the subjects

tend to mask this trend. It should be pointed out that al-

though the combined air flow ranges in vocal fry and modal

phonation overlap, there was no overlap within any one sub-

ject's mean flow rates during the two types of phonation.

That is, subjects with vocal fry flow rates relatively great-


er than the mean flow rates also had relatively greater modal

flow rates than the overall means at those two conditions. The

mean flow rates for each subject can be found in Appendix C.

A one-way analysis of variance with repeated measures

across subjects (Winer, 1962) was performed to determine if

the flow rates for the five conditions of phonation were sig-

nificantly different. Table 5 summarizes the analysis indi-

cating that the overall F-ratio was significant at the tested

level. When submitted to a Newman-Keuls test to determine what

conditions accounted for the overall significance, the data

indicate that the flow rates between vocal fry and modal

were significantly different at the .05 level, however, the

















Table 5. Summary of the analysis of variance
as a function of phonation conditions.


for air flow


Source of Sum of Mean
Variation Squares dF Square Fobt





Between Subjects 18.63 4 4.66
Within Subjects 76.84 20 3.84

Phonation Conditions 54.69 4 13.67 9.91*

Error 22.15 16 1.38


*Significant at the
(F.05,4,16= 3.01).


.05 level of confidence









flow rates within the vocal fry and modal conditions were

not statistically significant from each other. These re-

sults are summarized in Table 6. It may be concluded that

the subjects in this study produced relatively low pressures

in vocal fry compared to those produced during modal range

phonation.



Variations in Air Pressure and Flow in Vocal Fry Phonation

Another purpose of this study was to examine the mean

air pressure and air flow rate as they relate to repetition

rate and vocal intensity during vocal fry. As described

previously, subglottal pressures and flow rates were obtained

for three samples at each vocal fry condition. The data are

shown in Appendix D.


It should be noted that during the experiment, sub-

jects failed to produce repetition rates at the extremes of

their fry phonational ranges which were obtained prior to

the experiment. For example, the pre-experimental vocal

fry ranges (shown in Appendix A) varied from 22 to 92 Hz

while the experimental values ranged only from 40 to 90 Hz.

Nonetheless, as may be seen in Appendix D, relatively fast,


medium, and slow repetition rates were obtained for each

subject.

Relationship between repetition rate and subglottal pressure

In order to investigate the relationship between the

actual repetition rates and subglottal pressures produced by























* **




1- 11 )-i
-4 -4-4


(,-1


















cq
3l



























G Cl



>1

>, >,i~ a)tt


o o r
II a


C4






41

















U O0
0, o
c Om











a E






*i
c a a


O bfO

a a)



























j ^ Q)
0 a)
C O<
ao oa


O ma

-O


> k *H





0

0C-




-4 a)






U Z?


-4 > H






m *o









the subjects in this experiment, a Pearson Product-Moment

Correlation Coefficient (Hays, 1963) was computed between

subglottal pressure and repetition rate. A correlation of

.27 was found for this relationship, which when tested for

significance using a t-ratio, was found to be not signifi-

cant at the .05 level.

Relationship between repetition rate and air flow rate

A Pearson-r was computed between repetition rate and


mean rate of air flow during sustained phonation of the vowel

/a/. An r equal to -.29 was obtained and found to be non-

significant at the .05 level.

Intensity variations related to subglottal air pressure and
air flow rate

In view of the large variability in the subglottal

pressure measures and the variability observed in the rela-

tive intensity measures, an investigation of the relationships

between intensity changes and both subglottal pressure and air

flow rate was undertaken. Figure 5 is a plot of each subject's

mean subglottal air pressure as a function of the relative

intensity during phonation of the vowels /a/ and /i/. Fig-

ure 6 represents this relationship for the conditions with


the mouthpiece inserted. Figures 5 and 6 show that there is


a positive relationship between subglottal air pressure and

relative intensity. The Pearson Product-Moment Correlation

Coefficient computed between these two variables was .98.
























14 H


xxx


0


o
_o
0


0 0

0


I I I I I


I I 1 I i1
17 18 19 20 21
RELATIVE


I I !
22 23 24
INTENSITY (dB)


Figure 5. Mean subglottal pressure as a function of the
relative intensity for five subjects phonating the vowels
/a/ and /i/ in vocal fry. The values for /i/ are under-
lined.


I I
25 26















12



I I








9

10

E
0 8



w 7
n-
"-7


A s-i
X s-2
0 s-3
E S-4
0 ,S-5














El E


O
o
0"


I I I I I I
20 21 22. 23 24 25 26 27

RELATIVE INTENSITY (dB)

Figure 6. .Mean subglottal pressure as a function of the
relative intensity for five subjects phonating the vowel
/a/ in vocal fry with the mouthpiece in place.




42



In Figure 7 the mean rate of air flow is plotted-as a function

of the relative intensity. It can be seen that air flow rate


generally increased as a function of the relative intensity

and that the rate of increase varied from subject to subject.

For the five subjects used in the present investigation,


it may be concluded that subglottal pressure and air flow tend


to increase as vocal fry repetition rate increases. In addi-


tion, increases in subglottal pressure and to a lesser degree,


air flow,produced during vocal fry are related to increases


in the relative intensity level of vocal fry phonation.



















100 A

A s-i
90 X S-2
0 s-3
80- El S-4
0 S-5
SA
S 70 /?


o 60
-J
L A

-50 -
IL
0
u 40 -
I-


z 30 -


20 0E

x 0
10- 0


0 II I I I 1 I
20 21 22 23 24 25 26 27 28
RELATIVE INTENSITY (dB)


Figure 7. Mean air flow rate as a function of the
relative intensity for five subjects phonating the
vowel /a/ in vocal fry.















CHAPTER IV

DISCUSSION



The subjects in the present investigation utilized


essentially normal laryngeal mechanisms (as determined by the

subject-selection criteria) to produce vocal fry and mid-

range phonation which were found to be highly dissimilar in

terms of the aerodynamic measures accompanying them. The

results indicate that both the mean subglottal air pressure

and the mean air flow rate during vocal fry are significant-

ly different from those during low frequency modal phonation.

The subglottal pressures produced during vocal fry were

greater than those recorded in low modal phonation while

the mean rate of air flow during fry was less than that for

mid-range phonation. Subglottal pressure tended to increase

as a function of the repetition rate during vocal fry; it

decreased as the subjects went from approximately their 10

percent to their 30 percent mid-range frequencies. Air flow,

although highly variable during both types of phonation,

tended to decrease slightly as vocal fry repetition rate

increased. During modal phonation the mean air flow rates

were essentially the same for the two conditions. These









results and their relationships to previous studies are

discussed in the following paragraphs.



Subglottal Pressure and Type of Phonation

Prior to this study, no measures of subglottal pres-

sure during vocal fry phonation had been reported. Nonethe-

less the finding of relatively large subglottal pressures

departs somewhat from a previous prediction of low pressures

during vocal fry (Hollien, Moore, Wendahl, and Michel, 1966).

Several factors may be considered to account for the high

pressures. First of all, the subglottal pressure may increase

as the subject deviates from the region at which he usually


phonates. The results of this study and of Kunze's (1962)

show that the smallest subglottal pressures are in the region

usually used during normal conversation. Kunze found that as

a subject deviates either below or above the 30 percent fre-

quency in the modal phonational range, the subglottal pres-

sure tends to increase. In fact he found pressures in the

upper region of the modal range which were of the same gen-

eral magnitude as those found for vocal fry in this study.

The work of Flanagan and Langraf (1967) suggests a

possible explanation of the unexpected high pressures found

during vocal fry phonation. Using the variables of subglottal

pressure, vocal cord tension, and the properties of the con-

tacting surfaces of the folds at closure, Flanagan and Langraf








have shown that subglottal pressure is related to the duty

cycle of the wave form. Although their model is not specif-

ically related to vocal fry phonation, their calculated

values indicate that with a moderate amount of tension and

relatively long closed time, the accompanying subglottal pres-

sure is higher than at short closed times and extremely high

or low levels of tension. This model is in agreement with

earlier work by Van den Berg (1956) who suggested that when

the folds are vibrating with a long closed phase, the sub-

glottal pressures will be relatively large and produce a

rapid opening of the folds. He also suggests that if the

area of the opening is small, air flow rate could be expected

to be low. In fry the area of the opening appears to be tem-

porally small with respect to the total period (Coleman, 1968).

Therefore, pressure may build during the long closed phase and

then force apart the apparently large vocal fold mass.

The high pressures in fry may also be related to the

effects of the volume of air in the lungs at the beginning and

end of phonation. It has been reported by Draper, Ladefoged,

and Whitteridge (1957), by Kunze (1964),and by Perkins and

Yanagihara (1968) that pressure is greatest when lung volume

is greatest. In the present experiment, subjects produced

the fry and mid-range samples directly after inhalation,

that is at relatively large lung volumes. The obtained values









for air flow clearly indicate that the subject must retain

a relatively larger lung volume for a longer period of time

in vocal fry than in modal phonation. Consequently, high

pressures could be expected during sustained vocal fry pho-

nation when lung volume is relatively large. However, since


fry appears to occur normally at the ends of sentences and

phrases at relatively low lung volumes, it is not unlikely

that it could also be produced with low subglottal pressures.

There appears to be a need for additional research concerning

lung volume and subglottal pressure during vocal fry. In

particular, subglottal pressure should be measured at various


lung volumes when the speaker is reported to be phonating in


vocal fry.

The subglottal pressures obtained during the modal pho-


nation conditions of this study are in agreement with those

obtained by Kunze (1962) although it should be remembered

that he used the 10 and 30 percent points of the phonational

range including the falsetto frequencies. Therefore, although

the actual frequencies at which his subjects were phonating


were not reported, it may be assumed that they were phonating

at frequencies somewhat higher than the present subjects.

Nevertheless, he found a statistically significant drop in


pressure amounting to approximately one centimenter of water


as the subjects went from their 10 percent frequency to their

30 percent frequency of the modal-falsetto phonational range.








In the present study there was also a significant change in

the subglottal pressure between the two points of each sub-

ject's range; however, due to the variability both within

and between subjects, it can only be said that there was a

drop in pressure as the subjects approached their 30 percent


modal frequency from their 10 percent modal frequency region.


Air Flow and Type of Phonation


The flow rates found during vocal fry phonation tend

to agree with those previously reported by iMcGlone (1967).

Using a respirometer, he obtained flow rates ranging from


2.0 to 71.9 ml/sec. The present results are in general agree-

ment with McGlone's; however, the frequency ranges over which


air flow was measured in the two studies are somewhat different.

His subjects produced repetition rates ranging from 10.9 to

52.1 pps while the subjects in the present study had a com-

bined range from 39.7 to 90.4 pps. Neither study demonstrated

a significant relationship between repetition rate and air

flow rate while both showed that flow rate is highly variable

between subjects and within consecutive samples from the same

subject.

When compared to the flow rates-obtained for modal


phonation, the fry air flow values are considerably lower.

The mid-range flow rates in this study extended from 60.0

to 177.1 ml/sec. While this range overlaps the fry air flow

range, there was no overlap for any one subject. In general,








the mean air flow rates obtained during modal phonation for

the present subjects (107.6 and 121.7 ml/sec for the 10 and

30 percent frequencies respectively) agree with those ob-

tained by Kunze (1962), Isshiki (1964) and by Perkins and

Yanagihara (1968).

The flow rates recorded during vocal fry are generally

lower than those accompanying falsetto phonation. Isshiki's

(1964) lowest reported falsetto air flow rate was 59.4 ml/sec;

most of the fry values reported in this study and in MlcGlone's

(1967) are lower. Thus, it appears that the air flow associated

with the production of vocal fry is less than that for most

other phonational events. In this respect, the present data

support the prediction of Hollien, Moore, Wendahl, and Michel

(1966).


Effects of Vowels on Modal and Vocal Fry Phonation

The effects of the vowels upon the subglottal pressure

during vocal fry appear similar to results obtained for modal

range phonation (Ladefoged and McKinney, 1963). That is, dur-

ing vocal fry the /i/ was consistently associated with greater

subglottal air pressure than the /a/. When individual samples

of /a/ and /i/ produced by the same subject and having the

same relative intensity are compared, the subglottal pressures

are greater for phonation of /i/. Ladefoged and McKinney (1963)

report that for a given sound pressure level, subglottal pres-

sures produced during sustained phonation of /i/ are greater








than those produced during /a/. Thus, as one changes the

configuration of the vocal tract from /a/ to /i/, the sub-

glottal pressure is increased; a relationship can be noted

for vocal fry phonation also.

Effects of Intensity Changes

Consideration must also be given to the effects of

the relative intensity upon the fundamental frequency, sub-

glottal pressure, and air flow rate. Since the intensity

and the subglottal pressure varied simultaneously during

vocal fry phonation, it would appear that the effect of these

two variables on the repetition rate should be considered to-

gether. Although the subjects,with the help of the experimeter

attempted to control intensity, they appeared to increase in-

tensity as repetition rate increased during the practice and

the experimental sessions. Thus, with the present subjects,

it was not possible to completely separate the increases in

repetition rate and vocal intensity with respect to increases

in the subglottal pressure.

Variability Associated with Larvngeal Operation

Although there are certain consistent patterns in the

subglottal pressures of vocal fry and modal phonation which

have been demonstrated in this and other studies, some indi-

viduals appear to vary greatly in both the air pressure and

the air flow rate which accompanies phonation. This variabil-

ity may be the result of individuals exhibiting various patterns









of pressure/flow/frequency relationships as suggested by

Smith (1954) and Van den Berg (1958). For example, since

the lungs are highly elastic, the pressure created by their

recoil varies directly with their volume. Thus, while the

subjects inhaled prior to phonation, there is no way to

ascertain that they had inhaled maximally or that they all

began with the same lung volume for each phonation sample.

Furthermore, the task was one which demanded sophistication

in control of the intrinsic and extrinsic laryngeal muscula-

ture. Failure to maintain this high level of control may

have resulted in significant changes in phontaion. That

such changes occur has been demonstrated by Hollien (1962b),

Hollien and Mloore (1960) and Damste, Hollien, Moore, and

Murry (1968). These authors have shown that within the


framework of myoelastic-aerodynamic vocal fold operation,

small changes in vocal fold length and thickness may be asso-

ciated with relatively large changes in the fundamental fre-

quency of phonation. While changes in vocal fold length as

a function of the fry repetition rate have not been demon-

strated (Hollien, Damste, and Murry, 1969), additional in-

formation is needed to understand the relationships among

such variables as vocal fold tension, thickness, and repe-

tition rate during vocal fry.
















CHAPTER V


SUMMARY AND CONCLUSIONS



The purpose of this investigation was to determine

the subglottal pressure and air flow rates which accompany


vocal fry phonation. A secondary purpose was to examine

the relationships between the repetition rate in vocal fry


and the variables of subglottal air pressure and mean rate


of air flow. To achieve these purposes, simultaneous mea-


sures of the intratracheal air pressure, air flow rate, and


sound pressure during vocal fry and modal range phonation


were obtained. Recordings were made during sustained pho-


nation of two vcweis at tree vocal fry and two modal range


fundarme tal frequencies. The subgLcttal pressure sas measured


directly through a hypodermic needle inserted between the


first and second tracheal rings, air floA was measured through


a pneumotachograph inserted into the mouth, the sound pres-


sure was measured with probe tube microphone inserted into


the mouthpiece of the pneu-,otachograph. The voice signal,


subglottal pressure, and air flow were recorded simultaneously


on an oscillographic writer and FM magnetic tape recorder.


The subglottal air pressure and air flow rate recorded on









the multritrace oscillographic writer were sampled at 100 ms

intervals and converted into numerical values to estimate


the actual subglottal air pressure and air flow rate. Fun-


damental frequency was obtained from wave-to-wave measurements

of the voice signal. The data were submitted to statistical


analyses in order to test differences in pressure and flow


as they relate to fundamental frequency, vowel, and addition


of the mouthpiece to the recording apparatus.


From this investigation the following findings were

obtained:


1. The rate of air flow produced during vocal
fry is less than that produced during modal
range phonation. Although flow rate is
variable, there is no overlap in the modal
and vocal fry frequency ranges for individ-
uals.


2. Air flow rate does not seem related to
frequency of phonation in vocal fry or
modal range phonation.

3. Subglottal air pressures accompanying vocal
fry phonation were found to be greater than
those accompanying low frequency modal range
phonation.


4. There is a tendency for the subglottal pres-
sure to increase as vocal fry frequency
increases.


5. Subglottal pressure decreases as fundamental
frequency increases between the 10 and 30
percent frequencies in the modal range.

6. During vocal fry and modal range phonation,
the subglottal pressures for /i/ are greater
than those for /a/.









7. The addition of experimental apparatus for
recording air flow reduces*the subglottal
pressures during vocal fry and modal range
phonation.

8. Increases in subglottal pressure during
vocal fry are closely related to increases
in relative intensity; however, the rate of
increase appears to vary individually.



It appears, therefore, that sustained vocal fry pho-

nation results from a relatively low mean rate of air flow

compared to that in modal phonation. This conclusion, which

is also supported by data obtained using a respirometer

(McGlone, 1967),may relate to the characteristically long

closed phase of the vocal fry glottal wave form during which

time there is no air flow. It might also be expected that

flow rates accompanying vocal fry during any type of phona-


tion would also be relatively low since fry is most often


heard after lung volume is reduced, for example, at the ends

of sentences.


The subglottal pressures found during sustained vocal


fry phonation were relatively high in comparison with the

pressures in adjacent low modal range frequencies. However,

these pressures were of the same general magnitude as those

reported by others (Kunze, 1962; Isshiki, 1964) for phonation

at the upper portion of the phonational range. This appears

to suggest that as one departs from low frequency modal pho-

nation, glottal resistance increases and there is a need to




55



generate higher pressures to sustain vocal fold vibration.


This relationship observed for sustained phonation, however,

need not be the case during other types of phonation. For


example, vocal fry usually occurs briefly at the ends of


sentences having downward inflections when both lung volume


and intensity also decrease. Thus, it might be hypothesized


that relatively high pressures may not be required to produce


vocal fry. Indeed, it might be expected that these subglottal


pressures would not differ greatly from those directly pre-


ceding them in modal phonation




































APPENDIX A



PHONATIONAL RANGES
























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APPENDIX B



RECORDING SEQUENCE









Recording sequence followed throughout the experiment

A. Needle inserted; air flow recording apparatus disconnected.

Pressure recordings only

1. Slow fry* /a/
2. Slow fry /i/
3. Medium fry /a/
4. Medium fry /i/
5. Fast fry /a/
6. Fast fry /i/
7. Modal 10% /a/
8. Modal 10% /i/
9. Modal 30% /a/
10. Modal 30% /i/

B. Needle inserted; air flow recording apparatus inserted.

Pressure and flow recordings

1. Slow fry /a/
2. Medium fry /a/
3. Fast fry /a/
4. Modal 10% /a/
5. Modal 30% /a/




*The terms, slow, medium, and fast refer to the reference
signals. The samples which the subjects produced were later
grouped tc fit these categories.






























APPENDIX C


PROCEDURES FOR MEASURING SUBGLOTTAL
AIR PRESSURE AND RATE OF AIR FLOW











PROCEDURES FOR MEASURING SUBGLOTTAL
AIR PRESSURE AND RATE OF AIR FLOW



Measurement of the subglottal air pressure and rate


of air flow'were obtained from the analog output of a Multi-

trace Oscillographic Writer. The analog output is presented


schematically in Figure 8. This figure shows a reference

line (set to atmospheric pressure), the subglottal pressure

trace (Line A), the air flow trace (Line B), and the vertical

time lines placed at 100 ms intervals. To obtain the mean

subglottal pressure from this oscillogram, the distance from

the Reference Line to Line A was measured at 100 ms intervals.

The distance in centimeters at each point was then converted


to cm H20 by multiplying it by the calibration factor. The


average of 30 such measures resulted in the mean subglottal

air pressure for that particular sample.

The mean rate of air flow was obtained similar to


that for the pressure. The distance from the Reference Line

to Line B was measured in centimeters at 100 ms intervals and


multiplied by the appropriate calibration factor to produce


a flow rate in ml/sec.

























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INDIVIDUAL AND COMBINED MEANS OF THE FUNDAMEN-
TAL FREQUENCY, SUBGLOTTAL AIR PRESSURE, RATE
OF AIR FLOW, AND RELATIVE INTENSITY FOR PHONA-
TION OF /a/ AND /i/ AT FIVE FREQUENCY REGIONS




















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BIBLIOGRAPHY


Brackett, I., An analysis of the vibratory action of the
vocal folds during the production of tones at se-
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western University, 1947.

Coleman, R., Decay characteristics of vocal fry, Folia
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Coleman, R., Pulse patterns of vocal fry, Paper presented at
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Damste, H., Hollien,. H., Moore, P., and Murry, T., An x-ray
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Draper, M., Ladefoged, p., and Whitteridge, D.. Expiratory
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Draper, M., Ladefoged, P., and Whitteridge, D., Respiratory
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Hays, W. L., Statistics for Psychologists, New York: Holt,
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Hollien, H., and Curtis, J., A laminagraphic study of vocal
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Hollien, H., Damste, H., and Murry, T., Vocal fold length
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Hollien, H., and Moore, P., Measurements of the vocal folds
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Lieberman, P., Direct comparison of subglottal and esophageal
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McGlone, R., Air flow during vocal fry, Journal of Speech
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74




Van den Berg, J., Myoelastic-aerodynamic theory of voice
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BIOGRAPHICAL SKETCH


Thomas Murry was born September 10, 1943, at


Sewickley, Pennsylvania. In June, 1961, he was graduated

from Ambridge Senior High School, Ambridge, Pennsylvania.

He received a Bachelor of Science degree with a major in

Speech Pathology in May, 1964, from Indiana University of

Pennsylvania. In September, 1964, he enrolled in the

Graduate School of The Ohio State University where he was

a recipient of a Neurological and Sensory Disease Fellow-

ship. In May, 1965, he was graduated from The Ohio State

University with a Master of Arts degree with a major in

Voice Science. He enrolled in the Graduate School of the

University of Florida in September, 1966. He held a re-


search assistantship there until September, 1968, followed

by a faculty appointment as Interim Instructor until De-

cember, 1968.













This dissertation was prepared under the direction

of the candidate's supervisory committee and has been ap-

proved by all members of that committee. It was submitted

to the Dean of the College of Arts and Sciences and to the

Graduate Council, and was approved as partial fulfillment

of the requirements for the degree of Doctor of Philosophy.



March 25, 1969




Dean, Colle o A ts and Sciences




Dean, Graduate School



Supervisory Committee:




Chairman


I t-~it&v




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