Journal of Voice
Vok 3, No. 4, pp. 294-305
© 1989 Raven Press, Ltd., New York
Glottal Airflow and Transglottal Air Pressure
Measurements for Male and Female Speakers in Low,
Normal, and High Pitch
* t ~ : E v a B. H o l m b e r g , * t R o b e r t E. H i l l m a n , a n d t J o s e p h S. P e r k e l l
*Department of Communication Disorders, Boston University, Boston and ?Research Laboratory of Electronics,
Massachusetts Institute of Technology, Cambridge, Massachusetts, U.S.A.; ¢Department of Phonetics, Institute of
Linguistics, University of Stockholm, Stockholm, Sweden
Summary: Measurements on the inverse filtered airflow waveform and of estimated average transglottal pressure and glottal airflow were made from syllable sequences in low, normal, and high pitch for 25 male and 20 female
speakers. Correlation analyses indicated that several of the airflow measurements were more directly related to voice intensity than to fundamental frequency (Fo). Results suggested that pressure may have different influences in
low and high pitch in this speech task. It is suggested that unexpected results
of increased pressure in low pitch were related to maintaining voice quality,
that is, avoiding vocal fry. In high pitch, the increased pressure may serve to
maintain vocal fold vibration. The findings suggested different underlying laryngeal mechanisms and vocal adjustments for increasing and decreasing Fo
from normal pitch. Key Words: Inverse filter--Transglottal air pressure-Glottal airflow--Pitch--Male and female speakers.
male and female voices. The results are to be used
to understand more about normal vocal function
and, also, as norms for the evaluation of pathological voices (2).
The main purpose of this study was to establish
quantitative group data of a number of measures of
vocal function for normal male and female speakers
in normal, low, and high pitch. This is the second
part of a larger study, whose first part dealt with
intensity variation (1). In addition to measurements
of fundamental frequency (Fo) and intensity, we
used a noninvasive technique to derive measurements of transglottal air pressure and glottal airflow
from oral measurements of pressure and flow. Statistical analysis were performed to determine: (a)
relationships among measured parameters, (b) differences in measured parameters when Fo was
changed between conditions of normal and low and
normal and high pitch, and (c) differences between
BACKGROUND
Control of F o has been found to be a result of both
laryngeal adjustments and subglottal pressure (314). In high pitch, the longitudinal tension of the
vocal folds is increased (15), primarily by contraction of the cricothyroid muscle (8,11,12,16). Vocalfold thickness (17) and glottal area (18) decrease for
increased F0. The stiffness of the vocal-fold body is
increased by contraction of the vocalis muscle (16).
Raising of the entire larynx may also contribute to
the longitudinal tension, in addition to increasing
the tension of the vocal-fold surface in the vertical
direction (16).
In low pitch, the vocal folds are relatively short
Address correspondence and reprint requests to E. B. Holmberg at Research Laboratory of Electronics, Massachusetts Institute of Technology, Bldg. 36, Rm. 521, Cambridge, MA 02139,
U.S.A.
Presented in part at The 17th Symposium: Care of the Professional Voice, New York, June, 1988.
294
GLOTTAL A I R F L O W A N D T R A N S G L O T T A L A IR P R E S S U R E VS. P ITCH
and slack (12,16) and the vocal-fold mass per unit of
length is increased (17). Lowering F 0 involves relaxation of the cricothyroid muscle (12). Activity in
the extrinsic sternohyoid muscle has been observed
to lower the larynx, thereby helping to slacken the
vocal folds (J. J. Ohala cited in ref. 12). It has been
suggested that when the vocal folds are relatively
thick and slack, Bernoulli forces and subglottal
pressure have greater influence on the vibration
pattern (J. W. van den Berg cited in ref. 12). F o has
been found to be more sensitive to changes in subglottal pressure in the low F o region than at higher
frequencies (6,12).
Due to the inaccessible location of the larynx and
vocal folds, most techniques used to study vocal
function--such as tracheal puncture for subglottal
pressure measurements, electromyography, laminagraphy and high-speed motion pictures for studies of vocal fold movements--are more or less invasive; therefore, most studies have reported data
on a relatively small number of subjects. Since
there is wide variation of measures of glottal function across individuals (1,19), it should be useful to
study large numbers of subjects in order to capture
normal variability. The intent of the present study
was to examine a relatively large number of speakers using a noninvasive technique that allows us to
compare glottal airflow waveform measures with an
indirect measure of transglottal air pressure and
acoustic measures, thus providing new insight into
functional differences across pitch conditions and
between male and female voices.
METHODS
The procedures were designed to make possible
noninvasive recordings of laryngeal function for
large groups of subjects. A detailed description of
the recording, calibration, processing, and analyses
procedures, including underlying assumptions and
rationale for the measurements, can be found in
Holmberg et al. (1). A brief summary of the procedures is provided below.
Subjects, speech tasks, and recording
Forty-five adult native speakers of American English, 25 men and 20 women, with no history of
speech, voice, or hearing problems served as subjects. The average age for the men was 22 years and
5 months with a range of 17-30 years. The women,
who ranged from 18 to 36 years, had an average age
of 24 years and 3 months. The subjects were nonsmokers with no professional speaking or singing
training.
295
The speech material was chosen to allow for estimates of glottal function from oral measurements
(20-22) and consisted of strings of five repetitions of
the syllable/p~e/. The subjects produced the strings
in three pitch conditions, namely normal pitch,
lower than normal pitch, and higher than normal
pitch. In the interest of keeping the productions as
similar as possible to the subjects' natural speech,
the subjects were not asked to attain prescribed levels of pitch (or loudness), but instead were free to
use "comfortable" levels for each condition. The
only instruction given to the subjects v i s a vis pitch
was to not increase or decrease F o so much that
there was a possibility of using falsetto or fry registers. The subjects produced the syllable strings
five times per speech condition at a rate of -1.5
syUables/s.
The recordings were made in a sound-isolated
booth. Intraoral air pressure for the occlusion of the
stop consonant/p/was transduced using a translabial catheter connected to a differential pressure
transducer (Glottal Enterprises). Oral volume velocity (airflow) for the vowel/ae/was transduced by
means of a so called "Rothenberg mask" (a hightime resolution pneumotachograph, attached to a
circumferentially vented facemask; Glottal Enterprises) (20). The acoustic signal was recorded with
an external microphone (Model ECM 50; Sony) at a
fixed distance of 15 cm from the subjects' lips. The
signals were recorded on FM tape along with appropriate calibration signals, and monitored on an
oscilloscope.
Data analyses
The pressure, flow, and intensity signals were
low-pass filtered at different frequencies, digitized
simultaneously at two different sampling rates, and
processed further in software to produce "slowly
varying" and "glottal airflow" signals. From these
signals, data were extracted interactively, and measures were calculated (from the extracted data).
Figure 1 shows an example of the slowly varying
signals and measurement procedure. Average transglottal air pressure (cm H20) for the vowel was estimated by interpolation between peak intraoral air
pressures for the stop consonants in the syllable
string (1,20-22). Average airflow (L/s) through the
glottis, estimated from the smoothed oral airflow,
and intensity were measured for the vowel. Pressure, flow, and intensity values were also used to
define two general measures of glottal function:
"vocal efficiency," the ratio of intensity to the
Journal of Voice, Vol. 3, No. 4, 1989
296
E. B. H O L M B E R G E T AL.
MV
MV
MY
I
t
t
IIo
~-mnlll
_I
AIRFLOW
<
0 ----~
Ltl
.9.
>
PRESSURE
T
r
T
o
-
~ '
'
'
L
b
ae
;
I
p
ae:-
;
'
p
_
cl
.
'ae :}P
ae
:p
ae
u
I ~ec
FIG. 1. Example of slowly varying signals for one sequence of
five syllables and the mid-vowel (MV) location for data extraction. The traces from top to bottom correspond to intensity,
average airflow, and intraoral air pressure versus time,
product of air pressure times average flow (I/cm
H20 x L/s) (19,23) and "glottal resistance," to
airflow, the ratio of air pressure to average flow (cm
H20/L/s) (22). These measurements were made
at a vowel midpoint for the middle three syllables in
each string (making 15 tokens per pitch condition)
and averaged. The Fo (Hz) was measured (PM
Voice Analyzer; Voice Identification, Inc.) for each
of the 15 tokens per pitch condition and averaged to
obtain a F0 for each pitch condition.
The one token out of the 15 for each pitch condition that was closest to the mean for that condition in terms of F0 was located and used for inverse
filtering of the first formant (Fl). (The effects of
formants above F~ had been cancelled previously
by low-pass filtering in hardware.) The glottal airflow measures were made and averaged from the
four middle cycles of the inverse filtered token.
Figure 2 shows a stylized cycle and the glottal
airflow measurements. Time-based measures included: the fundamental period (7) (msec); open
quotient, the ratio of open time to the period [(h +
t2)/T)]; speed quotient, the ratio of opening to closing times (t~/t2); and closing quotient, the ratio of
closing time to the period (t2/T) (cf. ref. 27). Amplitude-based parameters (measured in L/s) were peak
flow, measured from the zero flow baseline to maximum flow; minimum flow (or "DC flow offset"),
measured from the zero flow baseline to the minimum during the closed phase (cf. refs. 23 and 28);
AC flow, calculated as peak flow minus minimum
Journal of Voice, Vol. 3, No. 4, 1989
FIG. 2. Airflow versus time for one glottal cycle. The glottal
airflow parameters are: the fundamental period (T), open quotient [(t] + t2)/T], speed quotient (t]/t2), closing quotient (tz/T) ,
peak flow (l/s), minimum flow (L/s), AC flow (L/s), AC/DC
(RMS of AC flow around its mean/mean of AC). [In addition,
maximum airflow declination rate (L/s 2) was extracted as the
maximum amplitude of the negative peak from the first
derivative.]
flow (cf. ref. 29); and the AC/DC ratio, the root
mean square (RMS) of the AC portion around its
mean divided by the mean of the AC portion (30). In
addition, the maximum flow declination rate (L/s 2)
was extracted as the maximum amplitude of the
negative peak of the first derivative of the airflow
signal.
Statistical analyses
Calculated summary statistics include means,
SDs, and ranges for the parameters in normal-,
low-, and high-pitch condition for men and women
separately. In analyses within low and high pitch
and for change between normal- to low- and normal- to high-pitch conditions, F o is given as a percentage of the Fo value in normal pitch. The following statistical analyses were performed.
(a) Pearson product moment correlations were
calculated to examine pair-wise linear relationships
between all parameter pairs. This was done within
each of the pitch conditions and for change (difference values) between normal to low and normal to
high pitch. In correlation analyses of parameters
with SPL, logt0 of each parameter was used. Two
GLOTTAL A I R F L O W A N D T R A N S G L O T T A L A IR P R E S S U R E VS. P ITCH
variables were considered to be highly correlated if
r was i>0.70, which means that at least 49% of the
variance is accounted for (i.e., r 2 = 0.49).
(b) Multivariate (Hotelling's T2) and univariate t
tests for paired comparisons were performed to determine which parameters were significantly altered
when pitch was manipulated (normal- to low-, and
normal- to high-pitch condition). Initial results from
the correlation analyses had shown that no parameters were strongly related to F 0, whereas there
were high correlations between SPL and some of
the parameters. Therefore, in addition to the above
t tests, analyses of covariance with SPL as the covariate were performed to examine parameter differences across the pitch conditions. For men and
women separately, values were " a d j u s t e d " for the
SPL difference that occurred across the pitch conditions (28,30). Thus, the effect of intersubject S P L
variation was reduced. To offset the problem with
artificially increased significant differences that can
be associated with such repeated univariate analyses, the tests for significant differences across pitch
conditions were performed at the conservative level
of p = 0.025. (In the following text, differences with
p values between 0.050 and 0.025 are referred to as
"nearly significant.")
(c) Analyses of covariance (covariate SPL) were
performed within each pitch condition to test for
significant differences between men and women.
low
0;5 1
o
~
pitch
/~
297
Values were " a d j u s t e d " for the cross-subject SPL
variation within each pitch condition (28,30). This
analysis is a type o f post hoc correction for the fact
that in all pitch conditions, men were 2-3 dB louder
than women. The tests for significant differences
between men and women were performed at the
conservative level of p = 0.025.
RESULTS
General observations on the glottal
airflow waveforms
Figures 3 and 4 show glottal airflow waveforms
for low, normal, and high pitch for six male and six
female speakers, respectively (A-F). The waveforms were chosen to show typical men's and women's waveforms as well as to illustrate qualitatively
the large intersubject variation that is reflected in
the quantitative data (cf. refs. 1 and 19). As seen in
both figures, the inverse filtering result was not always completely successful, and residuals of the F 1
are superimposed on some of the waveforms. The
residuals were seen mostly during the opening and
closed phases of the waveforms, and should not
affect our measurements to any great extent (cf.
ref. 1).
As seen in Figs. 3 and 4, in many cases for both
men and women, the flow waveform did not decrease c o m p l e t e l y to 0; there was a " D C flow
ncrmal pitch
high pitch
~ j ~ x . ~ J
~
tll
c
0
.=J
11
a:
FIG. 3. Glottal airflow versus time waveforms in low, normal, and high pitch for six
male speakers.
.C
,.J
A_.A_A_./
E
.A_/k_/
0
[~
.02
)~
TiME ($EC)
Journal of Voice, Vol. 3, No. 4, 1989
298
E. B. H O L M B E R G ET A L .
low pitch
normal pitch
high pitch
0.5-
B
A
IXI
O
,,d
t,
FIG. 4. Glottal airflow versus time waveforms in low, normal, and high pitch for six
female speakers.
¢
Q
-d
t~
o.s
]_~
jXJ%/~AJX.A
0
L.r
.02
, ,;~
TIME (SEC)
offset" during the portion of the waveform when
the glottis is assumed to be closed. This DC flow
offset was often larger than the 0.02-0.03 L/s that
can be due to vertical movements of the folds
(K. N. Stevens, 1987, unpublished data). Such a
DC flow offset has been found and discussed previously (cf. refs. 1,16,20,30,31). If there is a DC
flow offset in combination with a flat and welldefined closed portion (cf. Fig. 3, subject E, low
and normal pitch; Fig. 4, subject D, low pitch), the
membranous part of the glottis is likely to be closed
during the flat (closed) portion of the glottal waveform. The most plausible explanation for the DC
flow is that air is shunted through a posterior glottal
opening--a chinkmbetween the arytenoid cartilages (cf. ref. 32). In waveforms having a DC flow
offset in combination with a more rounded closed
portion (cf. Fig. 3, subject B in high pitch; Fig. 4,
subject A in high pitch), the closure and opening are
likely to be gradual with the glottal opening extending into the membranous part of the glottis. However, there are also waveforms with small or no DC
flow offset (cf. Fig. 3, subject D in normal and low
pitch; Fig. 4, subjects B in low pitch and E in normal pitch). The DC flow offset is represented by the
measurement "minimum flow." In the following,
we will refer to the portion of the glottal waveform
having the lowest flow as the "closed portion,"
even in cases of a DC flow.
Journal of Voice, Vol. 3, No. 4, 1989
The " f l a t n e s s " of the closed portion varied
across subjects and pitch conditions. In all pitch
conditions, some waveforms for both men and
women showed well-defined closed portions (cf~
Fig. 3, subjects A and E in low and normal pitch,
subject C in normal pitch, and subject F in low and
high pitch; Fig. 4, subject C in low and normal
pitch, subject D in low pitch, and subject E in normal and high pitch). However, there were also
waveforms with more gradual beginnings and ends
of the closed portions (cf. Fig. 3, subject A in high
pitch, subject B in low and high pitch; and less
clearly in Fig. 4, most subjects in high pitch).
Statistical results
In the Appendix, Tables A1-A6 show the summary statistics (unadjusted values) for normal, high,
and low pitch for male and female speakers.
For men, mean F 0 for normal pitch was 116 Hz
(SD = 12.0 Hz), with a range of 93-135 Hz. For the
high-pitch condition, the men increased Fo an average of 33% (of normal F0), with a range of 5-74% for
the individual speakers. For the low-pitch condition, the men decreased F0 an average of 13%, with
a range of 4-26%.
For women, mean Fo for normal pitch was 205 Hz
(SD = 24.0 Hz), with a range of 162-238 Hz for the
individual speakers. For the high-pitch condition,
the women increased F0 an average of 27% (of nor-
GLOTTAL A I R F L O W A N D TRANSGLOTTAL AIR P R E S S U R E VS. PITCH
mal F0), with a range of 9-43%. For the low-pitch
condition, the women decreased F0 an average of
11%, with a range of 4-21%.
Differences across pitch conditions
As described above, analysis of covariance (covariate SPL) was used to test for significant differences among pitch conditions.
Tables 1 and 2 summarize mean values in low,
normal, and high pitch for men and women speakers, respectively, after adjustment for SPL variation a c r o s s the p i t c h c o n d i t i o n s , i . e . , the
"adjusted" mean values that resulted from the analysis of covariance. Significant (as well as nearly
significant) differences across pitch conditions are
indicated with p values.
Differences between normal and high pitch
For both men and women, SPL increased significantly (p < 0.001) between the normal- and highpitch conditions. Men displayed significant differences between normal and high pitch in the unadjusted mean values for all parameters but glottal
resistance, speed quotient, and AC/DC ratio. For
women, the unadjusted values showed significant
299
differences for all parameters except glottal resistance, AC flow, minimum flow, speed quotient, and
AC/DC ratio. However, as seen in Tables 2 and 3,
most of these changes were no longer significant
after including SPL as a covariate. Therefore, these
changes were considered to be more strongly related to SPL than to F 0.
Aside from the obvious significant increase in Fo
for the higher pitched voices of both men and
women, the adjusted mean values for men showed
significant differences between normal and high
pitch for the following parameters: increased average flow (p = 0.007), increased open quotient (p <
0.001), and decreased AC/DC (p = 0.007). Nearly
significant differences were shown for the following
parameters: decreased glottal resistance (p =
0.037), increased minimum flow (p = 0.030), and
decreased speed quotient (p = 0.027). For women,
pressure increased significantly (p = 0.025) and
there was a nearly significant decrease in AC/DC (p
= 0.039).
Differences between normal and low pitch
There was no significant difference in SPL between normal and low pitch for men or women.
TABLE 1. Adjusted mean values and significant differences between normal and low,
and normal and high pitch in men a
Normal
Low
PER (ms)
MFDR (L/s 2)
ACFL (L/s)
PKFL (L/s)
MNFL (L/s)
OPQU [(t I + t2)/T]
SPQU (tl/t2)
CLQU (tz/T)
AC/DC
F o (Hz)
PRES (cm H20 )
AVFL (L/s)
GLRE (cm H20/L/s )
VOEF (I/cm H20 x L/s)b
9.8
246
0.24
0.35
0.10
0.58
1.86
0.20
0.60
101
7,1
0.17
44
11
p < 0.001
p < 0.001
p < 0.001
p = 0.001
Low
High
8.7
255
0.25
0.36
0.10
0.60
1.80
0.22
0.56
115
6.0
0.18
34
11
8.7
309
0.27
0.38
0.09
0.59
1.84
0.21
0.62
119
6.6
0.18
38
16
High
6.6
309
0.26
0.43
0.14
0.68
1.55
0.25
0.45
151
6.8
0.23
32
15
p < 0.001
(p = 0.030)
p < 0.00t
(p = 0.027)
p = 0.007
p < 0.001
p = 0.007
(p = 0.037)
" Significant (p < 0.025) and close to significant (p < 0.050) differences between normal and low and
normal and high pitch for adjusted values (covariate SPL) of the following parameters: period (PER),
maximum flow declination rate (MFDR), AC flow (ACFL), peak flow (PKFL), minimum flow
(MNFL), open quotient (OPQU), speed quotient (SPQU), closing quotient (CLQU), AC/DC, Fo,
pressure (PRES), average flow (AVFL), glottal resistance (GLRE), and vocal efficiency (VOEF).
Values for normal pitch can differ for analyses of change between normal and low, and normal and
high pitch because the number of subjects in the two comparisons are different. This is because three
subjects did not lower Fo for the low-pitch condition. Therefore, two values for normal pitch are listed
in the tables: one value from analysis between normal versus low pitch, the other from normal versus
high pitch. Nearly significant p values are shown in parentheses.
b Values for VOEF have been multiplied by 105.
Journal of Voice, Vol. 3, No. 4, 1989
300
E. B. H O L M B E R G E T A L .
TABLE 2. Adjusted mean values and significant differences between normal and low,
and normal and high pitch in w o m e n a
Normal
Low
PER (ms)
MFDR (L/s2)
ACFL (L/s)
PKFL (L/s)
MNFL (L/s)
OPQU [(tl + t2)/T]
SPQU (tl/t2)
CLQU (tz/T)
AC/DC
F 0 (Hz)
PRES (cm H20)
AVFL (L/s)
GLRE (cm HzO/L/s)
VOEF (I/cm H20 × L/s) b
5.5
170
0.14
0.24
0.08
0.68
1.57
0.26
0.41
182
6.0
0.13
46
9
p < 0.001
p = 0.024
p < 0.001
(p = 0.027)
Low
High
4.9
160
0.13
0.22
0.08
0.74
1.62
0.28
0.37
203
5.8
0.14
41
9
4.8
175
0.14
0.23
0.08
0.74
1.62
0.28
0.39
207
6.0
0.14
42
11
High
3.9
168
0.13
0.23
0.09
0.87
1.48
0.35
0.32
252
6.3
0.16
41
11
p < 0.001
(p = 0.039)
p < 0.001
p = 0.025
a See Table 1, footnote a for details regarding data and definitions of abbreviations.
b Values for VOEF have been multiplied by 105.
Therefore, there were only small differences between the unadjusted and adjusted mean values,
and few parameters changed significantly. Aside
from the obvious significant decrease in F0, the adjusted mean values for men showed significant increases in pressure (p < 0.001) and glottal resistance (p = 0.001), whereas for females open quotient decreased significantly (p = 0.024). The
pressure increase for women was nearly significant
(p = 0.027).
TABLE 3. Adjusted mean values f o r men and women
and significant differences in normal pitch between men
and women a
Differences between men and women
Tables 3-5 compare men's and women's adjusted
mean values within the normal-, high-, and lowpitch conditions. Significant (as well as nearly significant) differences between men and women are
indicated with p values.
As expected, men had significantly lower Fo in all
pitch conditions (p < 0.001). In the normal pitch
condition (Table 3), in comparison with women,
men had significantly higher maximum flow decliT A B L E 4. Adjusted mean values Jbr men and women
and significant differences in high pitch between men
and women a
Adjusted mean
F o (Hz)
PRES (cm H20 )
AVFL (L/s)
GLRE (cm H20/L/s)
VOEF (I/cm HzO x L/s) b
MFDR (L/s2)
ACFL (L/s)
PKFL (L/s)
MNFL (L/s)
OPQU [(q + t2)/T]
SPQU (tl/t2)
CLQU (tJT)
AC/DC
Adjusted mean
Men
Women
p
119
5.9
0.19
33
9
239
0.23
0.35
0.10
0.61
1.79
0.22
0.52
207
6.1
0.14
44
12
117
0.14
0.23
0.08
0.74
1.67
0.28
0.40
<0.001
-0.005
0.006
(0.033)
<0.001
<0.001
<0.001
-<0.001
-<0.001
0.009
Adjusted mean values for men and women in normal pitch.
Significant differences are indicated with p values. Nearly significant p values are shown in parentheses.
b Values for VOEF have been multiplied by 105.
See Table 1, footnote a for definitions of abbreviations.
Journal of Voice, Vol. 3, No. 4, 1989
F o (Hz)
PRES (cm H2O)
AVFL (L/s)
GLRE (cm H20/L/s)
VOEF (l/cm H20 × L/s) b
MFDR (L/s z)
ACFL (L/s)
PKFL (L/s)
MNFL (L/s)
OPQU [(t~ + tz)/T]
SPQU (tl/t2)
CLQU (tz/T)
AC/DC
Men
Women
p
151
6.9
0.23
31
15
304
0.26
0.42
0.14
0.66
1.56
0.24
0.46
263
7.1
0.16
45
20
220
0.16
0.26
0.09
0.85
1.50
1.34
0.37
<0.001
-0.002
0.002
0.015
<0.001
<0.001
<0.001
(0.026)
<0.001
-<0.001
(0.051)
a Adjusted mean values for men and women in high pitch.
Significant differences are indicated with p values. Nearly significant p values are shown in parentheses.
b Values for VOEF have been multiplied by 105.
See Table 1, footnote a for definitions of abbreviations.
GLOTTAL A I R F L O W A N D T R A N S G L O T T A L A IR P R E S S U R E VS. P ITCH
T A B L E 5. A d j u s t e d m e a n values for men and w o m e n
and significant differences in low pitch between m e n
and w o m e n a
Adjusted m e a n
Fo (Hz)
P R E S (cm H20 )
A V F L (L/s)
G L R E (cm H20/L/s)
V O E F (I/cm H 2 0 x L/s) b
M F D R (L/s 2)
A C F L (L/s)
P K F L (L/s)
M N F L (L/s)
O P Q U [(t~ + t2)/T]
S P Q U (q/t 2)
C L Q U (tJT)
AC/DC
Men
Women
p
100
6.6
0.16
42
8
214
0.23
0.33
0.10
0.59
1.79
0.21
0.56
200
6.2
0.14
46
11
182
0.15
0.24
0.08
0.67
1.59
0.26
0.42
<0.001
----(0.028)
<0.001
0.002
-0.011
-0.005
0.006
a Adjusted m e a n values for m e n and w o m e n in low pitch. Significant differences are indicated with p values. Nearly significant p values are s h o w n in parentheses.
b Values for V O E F h a v e been multiplied by 105.
See Table 1, footnote a for definitions of abbreviations.
nation rate (p < 0.001), higher peak flow (p <
0.001), higher AC flow (p < 0.001), higher average
flow (p = 0.005), smaller open quotient (p < 0.001),
smaller closing quotient (p < 0.001), higher AC/DC
ratio (p = 0.009), and lower glottal resistance (p =
0.006). A nearly significant difference was found for
vocal efficiency (p = 0.033), which was lower for
the men. No significant differences between men
and women were found for pressure, minimum
flow, or speed quotient.
In the high-pitch condition (Table 4), in addition
to the significant differences between men and
women found for normal pitch, men had significantly lower vocal efficiency (p = 0.015). Minimum
flow (p = 0.026) and AC/DC (p = 0.051) were
higher for the men by a nearly significant difference. No significant differences between men and
women were found for pressure or speed quotient.
In the low pitch condition (Table 5), there were
fewer differences between men and women in parameters than for the other conditions. Men had
significantly higher AC flow (p < 0.001), higher
peak flow (p = 0.002), smaller open quotient (p =
0.011), smaller closing quotient (p = 0.005), and
higher AC/DC (p = 0.006). The higher maximum
flow declination rate for men was close to significant (p = 0.028). No significant differences between men and women were found for pressure,
average flow, glottal resistance, vocal efficiency,
minimum flow, or speed quotient.
301
DISCUSSION
Large intersubject variation was found in all pitch
conditions. This finding agrees with reports in previous studies of air pressure and airflow (1,19).
Some of the variation in our pitch data could be due
to the possibility that some subjects may have used
falsetto register in the high-pitch condition in spite
of instructions designed to elicit the chest register.
To avoid this problem in future studies, it may be
preferable to control pitch to a greater extent when
the recordings are made (33).
No parameters correlated strongly with Fo,
whereas there were high correlations between some
parameters and SPL. Some of the variation in parameters across subjects and conditions was therefore likely to have been due to variation in SPL,
which was the primary reason that SPL was treated
as a covariate in testing for significant differences.
It should be noted that the results of such analyses
cannot be interpreted as directly reflecting the
physical significance of the measures that we obtained. One somewhat more direct way of studying
which parameters are related to pitch change would
be to ask the subjects to change pitch while keeping
intensity constant. However, since a change in
number of air pulses per unit of time in itself would
contribute to a change in SPL, the subjects might
have to manipulate their phonation in some way to
keep SPL constant, and the result would not reflect
normal vocal function. Therefore, in this study, we
considered the statistical post hoc adjustments for
SPL variation to be potentially less confounding
than attempting to directly control F o and SPL.
Since SPL is inseparable from F 0 in natural speech,
the only way to study pitch and loudness separately
may be with modeling.
Within pitch conditions, air pressure was somewhat higher for men than for women, but when the
influence of the higher male SPL was factored out,
there was no significant difference between men
and women in pressure. Therefore, glottal waveform differences between men and women (post
SPL adjustment) were not primarily due to differences in respiratory force.
With increasing F0 from the normal- to high-pitch
condition, SPL increased significantly for both men
and women, and a majority of the speakers increased pressure. However, for men after adjusting
for the SPL increase, the pressure increase was not
significant, suggesting that the pressure increase
Journal of Voice, Vol. 3, No. 4, 1989
302
E. B. H O L M B E R G ET AL.
was more related to the increased SPL than to F 0.
In agreement with previous work (cf. ref. 12), these
results suggest that for men increased F 0 between
the normal- and high-pitch conditions was achieved
primarily by laryngeal adjustments rather than by
increased respiratory forces. In contrast, for
women the pressure increase between normal and
high pitch was significant after adjusting for SPL.
The women's results suggest, at least statistically,
that pressure was related not only to the SPL increase but also to the increased F 0. Further research is needed to explore the physical significance of these differences b e t w e e n men and
women.
Previous research has generally shown a positive
relationship between subglottal pressure and F0
during sustained vowel phonation (4,10), and during
sudden pushes on subjects' chest (13). Subglottal
pressure has also been found to drop with Fo at
sentence endings (12). Therefore, the present findings of increased pressure (in adjusted as well as
unadjusted values) for low pitch were unexpected.
We speculate that the discrepancy between the previous results and our data may be due to the use of
different speech tasks. It is conceivable that Fo during sustained phonation of vowels may covary with
subglottal pressure in a more systematic way,
whereas syllable repetitions in low- and high-pitch
conditions may demand different vocal adjustments
and represent different speech modes (cf. refs. 6
and 12). Our findings of increased pressure in low
pitch are somewhat supported by results reported
by Kunze (4). He found for 10 male speakers that
subglottal pressure increased with increased F 0 with
the exception of the lowest F0, where pressure was
somewhat higher than for the second lowest F0
level.
Increased pressure in high pitch was accompanied by increased AC flow (cf. refs. 1 and 26),
whereas in low pitch the increased pressure instead
was accompanied by decreased AC flow. We speculate that for the speech task used in this study (i.e.,
syllable repetition) there may be different mechanisms for increasing and decreasing pitch, and that
pressure may have different functions in the high
and low pitch conditions. In high pitch, when the
vocal folds are tense and stiff, increased pressure
may be necessary to sustain vocal fold vibration. In
low pitch, when the vocal folds are relatively slack,
increased pressure may serve as a stabilizing factor
to maintain voice quality, i.e., to prevent vocal fry.
Journal of Voice, Vol. 3, No. 4, 1989
Further work is needed to explore the mechanism
underlying these findings for pressure.
Holmberg et al. (1) found that many of the glottal
airflow parameters measured in this study changed
significantly with increased or decreased intensity
across conditions of soft, normal, and loud voice.
As described above, in this study several of these
parameters (maximum flow declination rate, AC
flow, open quotient, speed quotient, and closing
quotient) changed significantly across the pitch conditions, but, after covariation with SPL, these
changes were no longer significant. These results,
in combination with low correlations between F 0
and all of the parameters, and high correlations between SPL and some of the parameters (pressure,
maximum flow declination rate, AC flow, and vocal
efficiency), suggest that the measures used in this
study are not primarily indicative of parameters determining Fo, such as tension and stiffness of the
vocal folds. Instead they may be more directly related to characteristics of the sound source that determine intensity (cf. ref. 34)[
CONCLUSIONS
The results of this study indicate that several of
the glottal airflow measurements that were obtained
are more directly related to voice source characteristics that determine intensity than to factors that
determine F 0, such as vocal fold tension and stiffness. Some results suggest that for the speech utterance used (syllable repetition), the conditions of
low, normal, and high pitch may represent different
speech modes rather than reflecting conditions in
which there is a continuous change of Fo. Results
further suggest that the subglottal pressure may
have a different function in the production of this
utterance at low versus high pitch.
Even though pitch variation may be less important than intensity variation as a way of eliciting
useful measures of glottal function with these techniques, this data base should be of importance for
research of normal voice function, as well as for
clinical research of voice diagnostic and therapy
techniques that require patients to manipulate F 0.
Acknowledgment: This research was supported by the
National Institutes of Health, grant number RO1
NS21183. We wish to thank Kenneth Stevens for many
helpful comments.
APPENDIX
TABLE A1. Summary statistics: normal pitch in men
TABLE A3. Summary statistics: low pitch in men
(n =
25)
(n = 25)
Slowly varying parameters"
SPL (dB)
79
F o (Hz)
116
PRES (cm H20 )
6.3
A V F L (L/s)
0.19
G L R E (cm HzO/L/s )
38
V O E F (I/cm H20 × L/s) b
16
Glottal waveform parameters ¢
SPL (dB)
79
PER (ms)
8.6
M F D R (L/s 2)
280
P K F L (L/s)
0.38
A C F L (L/s)
0.26
M N F L (L/s)
0.12
0.60
OPQU [(q + tz)/T]
SPQU (ta/t 2)
1.82
0.22
C L Q U (t2/T)
AC/DC
0.60
PRES (cm H20)
6.4
A V F L (L/s)
0.20
G L R E (cm HzO/L/s )
37
V O E F (I/cm H20 × L/s) b
16
SD
Range
3
12
1.4
0.07
17
13
73-86
93-135
4.2-9.6
0.10-0.35
12-77
2-62
3
1.0
90
0.09
0.07
0.07
0.07
0.28
0.04
0.23
1.4
0.07
18
13
73-87
7.3-10.9
140-470
0.21-0.54
0.16-0.42
0.02-0.30
0.46-0.77
1.32-2.58
0.14-0.27
0.23-1.12
4.3-9.7
0.0%0.36
14-85
2-62
a Averaged over 15 tokens.
b Values for V O E F have been multiplied by 105.
c Averaged over four cycles of the selected token.
See Table 1, footnote a for definitions of abbreviations.
TABLE A2. Summary statistics: high pitch in men
(n = 25)
Slowly varying parameters a
SPL (dB)
83
Fo (Hz)
155
PRES (cm H20)
7.5
A V F L (L/s)
0.24
G L R E (cm HzO/L/s )
36
VOEF (I/cm H20 × L/s) b 30
Glottal waveform parameters C
SPL (dB)
83
PER (ms)
6.6
M F D R (L/s 2)
365
P K F L (L/s)
0.45
A C F L (L/s)
0.29
M N F L (L/s)
0.16
OPQU [(t 1 + t2)/T]
0.66
1.65
SPQU (tl/t 2)
CLQU (t2/T)
0.24
AC/DC
0.53
PRES (cm H20 )
7.4
A V F L (L/s)
0.25
GLRE (cm HzO/L/s)
35
VOEF (I/cm H20 x L/s) b 28
Slowly varying parameters a
SPL (dB)
F o (Hz)
PRES (cm H20 )
A V F L (L/s)
G L R E (cm HzO/L/s)
V O E F (I/cm H20 x L/s) b
Glottal waveform parameters"
SPL (dB)
PER (ms)
M F D R (L/s 2)
P K F L (L/s)
A C F L (L/s)
M N F L (L/s)
OPQU [(t 1 + t2)/T]
SPQU (tl/t 2)
C L Q U (t2T)
AC/DC
PRES (cm H20)
A V F L (L/s)
G L R E (cm HzO/L/s )
V O E F (I/cm H20 x L/s) b
Range
4
19
1.7
0.09
17
32
7%92
122-191
5.2-12.4
0.13-0.47
13-93
5-136
4
0.8
148
0.10
0.07
0.08
0.08
0.46
0.06
0.23
1.9
0.10
19
33
77-92
5.2-8.1
208-827
0.27-0.65
0.20-0.43
0.03-0.32
0.4%0.79
0.50-2.66
0.10-0.39
0.26-1.11
4.6-13.0
0.11-0.44
12-94
3-124
a Averaged over 15 tokens.
b Values for V O E F have been multiplied by 105.
c Averaged over four cycles of the selected token.
See Table 1, footnote a for definitions of abbreviations.
SD
Range
79
101
7.0
0.18
46
12
3
10
1.6
0.08
20
7
74-85
82-124
4.%11.1
0.09-0.40
12-84
2-27
78
9.9
245
0.36
0.25
0.11
0.59
1.88
0.21
0.60
6.9
0.18
44
t0.3
3
1.0
90
0.10
0.07
0.06
0.10
0.50
0.06
0.15
1.7
0.07
17
6.7
73-84
8.0-12.1
124-430
0.20-0.58
0.15-0.39
0.04-0.32
0.45-0.83
0.96-2.88
0.12-0.31
0.24-0.86
4.6-11.0
0.0%0.40
12-71
1.7-27
" Averaged over 15 tokens.
b Values for V O E F have been multiplied by 105.
c Averaged over four cycles of the selected token.
See Table 1, footnote a for definitions of abbreviations.
TABLE A4. Summary statistics: normal pitch in women
(n =
SD
X
20)
Slowly varying parameters a
SPL (dB)
76
F o (Hz)
205
PRES (cm H20 )
5.8
A V F L (L/s)
0.14
GLRE (cm H20/L/s)
42
V O E F (I/cm H20 × L/s) b
11
Glottal waveform parameters C
SPL (dB)
76
PER (ms)
4.9
M F D R (L/s 2)
164
P K F L (L/s)
0.22
A C F L (L/s)
0.14
M N F L (L/s)
0.09
OPQU [(t~ + tz)/T]
0.76
1.65
SPQU (tJt2)
0.29
C L Q U (t2/T)
AC/DC
0.38
PRES (cm H20)
5.8
A V F L (L/s)
0.14
G L R E (cm HzO/L/s )
43
V O E F (I/cm H20 × L/s) b
11
SD
Range
4
24
0.9
0.03
8
9
67-81
162-238
4.4-7.6
0.09-0.21
28-93
1-38
4
0.6
58
0.06
0.05
0.04
0.10
0.30
0.04
0.13
1.1
0.03
9
9
67-81
4.1-6.2
91-279
0.12-0.37
0.0%0.25
0.01-0.16
0.56-0.95
1.1%2.33
0.20-0.37
0.25-0~80
3.6-8.1
0.09-0.22
30-62
2-36
Averaged over 15 tokens.
b Values for V O E F have been multiplied by 105.
c Averaged over four cycles of the selected token.
See Table 1, footnote a for definitions of abbreviations.
304
E. B. HOLMBERG
TABLE A5. S u m m a r y statistics: high pitch in w o m e n
(n = 20)
X
Slowly varying parameters a
SPL (dB)
80
Fo (Hz)
261
PRES (cm HzO)
6.7
AVFL (L/s)
0.17
GLRE (cm H20/L/s)
43
VOEF (I/cm H20 × L/s) b
18
Glottal waveform parameters c
SPL (dB)
80
PER (ms)
3.8
MFDR (L/s 2)
201
P K F L (L/s)
0.25
ACFL (L/s)
0.15
MNFL (L/s)
0.10
0.87
OPQU [(q + t2)/T]
SPQU (tl/t2)
1.52
0.35
CLQU (tE/T)
AC/DC
0.36
PRES (cm H20 )
6.6
AVFL (L/s)
0.16
GLRE (cm HEO/L/s)
44
VOEF (I/cm H20 x L/s) b
19
SD
Range
4
30
0.8
0.04
11
12
72-85
204-309
4.6-8.1
0.09-0.24
30-75
3-51
4
0.5
68
0.07
0.05
0.04
0.12
0.33
0.04
0.10
1.0
0.04
ll
18
70-86
3.1-4.9
98-317
0.14-0.39
0.07-0.26
0.03-0.20
0.61-0.99
0.90-2.08
0.27-0.42
0.18-0.60
4.5-8.6
0.09-0.26
27-70
3-83
a Averaged over 15 tokens.
b Values for VOEF have been multiplied by 105.
c Averaged over four cycles of the selected token.
See Table 1, footnote a for definitions of abbreviations.
TABLE A6. S u m m a r y statistics: low pitch in women
(n = 20)
Slowly varying parameters a
SPL (dB)
F o (Hz)
PRES (cm HzO)
AVFL (L/s)
GLRE (cm HzO/L/s )
VOEF (I/cm H20 × L/s) b
Glottal waveform parameters c
SPL (dB)
PER (ms)
MFDR (L/s 2)
P K F L (L/s)
ACFL (L/s)
MNFL (L/s)
OPQU [(tl + t2)/T]
SPQU (tl/t z)
CLQU (t2/T)
AC/DC
PRES (cm HzO)
AVFL (L/s)
GLRE (cm H20/L/s)
VOEF (I/cm H20 x L/s) b
SD
Range
77
182
6.1
0.14
49
11
4
22
0.8
0.05
23
10
6%80
134-214
4.5-7.6
0.05-0.26
2%112
2-41
77
5.5
180
0.25
0.15
0.10
0.68
1.58
0.27
0.44
6.1
0.14
49
12
4
0.8
68
0.08
0.06
0.05
0.09
0.19
0.04
0.21
1.0
0.05
23
13
68-81
4.5-7.4
78-296
0.15-0.42
0.07-0.27
0.01-0.20
0.52-0.89
1.26-1.87
0.1%0.38
0.20-0.08
4.7-8.1
0.05-0.26
31-108
2-57
a Averaged over 15 tokens.
b Values for VOEF have been multiplied by 105.
c Averaged over four cycles of the selected token.
See Table 1, footnote a for definitions of abbreviations.
Journal of Voice, Vol. 3, No. 4, 1989
ET-AE.
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