Efectos Del Volumen Pulmonar en Eficiencia Vocal

Journal of Voice Vol. 12, No. 4, pp. 424-433 1998 Singular Publishing Group, Inc.

Effects of Lung Volume on the Glottal Voice Source

*Jenny Iwarsson, -[Monica Thomasson, and tJohan Sundberg

*i'Department of Speech, Music, and Hearing, Royal Institute of Technology ( KTH), Stockholm, Sweden and *Department of Logopedics and Phoniatrics, Karolinska Institute, Huddinge University Hospital, Huddinge, Sweden

Summary: According to experience in voice therapy and singing pedagogy, breathing habits can be used to modify phonation, although this relationship has never been experimentally demonstrated. In the present investigation we examine if lung volume affects phonation. Twenty-four untrained subjects phonated at different pitches and degrees of vocal loudness at different lung volumes. Mean subglottal pressure was measured and voice source characteristics were analyzed by inverse filtering. The main results were that with decreasing lung volume, the closed quotient increased, while subglottal pressure, peak-to-peak flow amplitude, and glottal leakage tended to decrease. In addition, some estimates of the amount of the glottal adduction force component were examined. Possible explanations of the findings are discussed. Key Words: Phonation--Lung volume--Adduction--Subglottal pressure--Voice source--Tracheal pull.

It is a common experience in clinical voice therapy, as well as in singing pedagogy, that an appropriate breathing strategy has important effects on phonation. While different techniques are used for achieving such a breathing function, the goal seems to be the same: a desirable voice quality and vocal health. Many voice disorders, especially in women, are functional, i.e., caused by inappropriate phonatory habits (1). Among such voice patients, hyperfunction and a pressed voice quality, caused by an exaggerated glottal adduction, are frequently observed. An ap-

Accepted for publication February 26, 1997. Address correspondence and reprint requests to: Jenny Iwarsson, Dept. of Speech, Music, and Hearing, KTH,

Drottning Kristinas v~ig 31, SE-100 44 Stockholm, Sweden. This paper was presented at the 25th Annual Symposium:

Care of the Professional Voice, June 3-9, 1996, Philadelphia, Pennsylvania, U.S.A.

propriate treatment is often voice therapy where one important component is to give the patient an ade- quate breathing technique. This strongly suggests that breathing behavior affects vocal fold vibration.

Some support for this idea has been found in previous investigations. Hoit and coworkers studied the connection between lung volume (LV) and voice onset time, the time from the release of a voiceless stop sound to full vocal fold vibration amplitude (2). They found that voice onset time was longer with high LV, than with low LV. This finding supports the idea of a connection between LV and a glottal abduction force component.

A plausible explanation of the phonatory effect of LV is the tracheal pull, which represents a mechanical link between the breathing and phonatory appa- ratus and implies that the elasticity of the trachea ex- erts a caudally directed force on the larynx (3-7). According to Zenker and others, the tracheal pull is associated with a glottal abduction force (Fig. 1).

424

EFFECTS OF LUNG VOLUME ON THE GLOTTAL VOICE SOURCE 425

FIG. 1. Schematic illustration of Zenker's idea (1964, p. 22) that a caudally directed force on the larynx (solid arrows) widens the glottis, and hence can be assumed to generate a mechanical abductive force component (dashed anvws).

"The arrangement of laryngeal mucous membrane and connective tissue plates in its environment caus- es a widening of the glottis in unfixed specimens when the trachea is pulled downward" (5,p22).

According to Macklin (8), the carina position, and hence also the tracheal pull, varies with LV; he found that the carina caudally moved about 21 mm during inhalation. Because of the trachea's elasticity, such a movement must modulate the tracheal pull, and hence also the abductive glottal force component. As pointed out by Fink and Demarest (9) and Brancatisano et al. (10), laryngeal adjustment varies during the breathing cycle; inspiration is typically associated with a widening of the glottis due to a separation of the arytenoid cartilages. Furthermore, the glottis opening has been found to be positively correlated to LV, both during panting and during continous, expiration (11).

In summary, previous research shows the possibility that a variation in LV induces a variation of an abductive force component in the glottis. Glottal abduction is also obviously relevant to phonation; a

decreased abduction results in a lower vocal fold vibration amplitude and a longer closed phase, and hence a smaller amplitude of the airflow pulses through the glottis (12-14). The aim of the present study was to experimentally test if LV affects the glottal voice source during phonation.

METHODS

Experiment Eighteen males and 14 females, with ages of 21-54

years, volunteered for this study. None of them had had any voice training and all lacked singing experience. This type of subject was preferred, as voice training can be assumed to induce behaviors that may conceal mechanical effects of breathing behavior on phonation. All subjects were unaware of the purpose of the study.

The independent variable in the experiment was LV. Standing in an upright position, the subjects repeated the syllable/pae:/ starting at maximum LV and continuing until they ran out of breath. The pro- cedure was repeated at three pitches and in medium, soft, and loud phonation, respectively. The subjects were instructed to expand their abdominal walls during inhalation, as such an expansion is a safe sign of lowering the diaphragm (15). Also, this inhalation pattern is practiced in voice therapy as well as in singing pedagogy. The signal representing this expansion was displayed as a visual feedback on an oscilloscope screen.

The experimental setup is illustrated in Fig. 2. A respiratory inductive plethysmograph (Respitrace TM, Ambulatory Monitoring, Inc., Ardsley, NY) equipped with elastic transducers (Respibands) was used to document LV and breathing behavior. The upper ribbon was placed on the rib cage and the lower ribbon was on the abdominal wall, just below the navel. The signals from the two respibands and their sum were displayed on a mingograph (Siemens 34T). First, the subjects performed isovolume maneuvers while the amplification of the chest and abdominal signals were adjusted so that the sum reflected relative LV. They also performed maximum inhalations and ex- halations, to determine vital capacity. Finally, they performed a series of relaxed sighs revealing the re- laxation expiratory level (REL).

Journal of Voice, Vol. 12, No. 4, 1998

426 JENNY IWARSSON ET AL.

OSCILLOSCOPE DI

, ooo

I CHEST ~ MIC

ABD. WALl FLOW

FIG. 2. Block diagram of the experimental setup. The following signals were recorded on the DAT FM recorder: audio signal (MIC), airflow from the mask (FLOW), subglottal pressure (Ps) and the Respitrace signals showing rib cage (CHEST), abdomen (ABD WALL), and lung volume (E). The last three signals were also displayed on a mingograph. The signal from the lower respiband was shown to the subjects on an oscilloscope screen as visual feedback.

The audio signal was picked up at a constant dis- tance of 30 cm by a high-fidelity microphone (Sony ECM 959 DT). Mean subglottal pressure was cap- tured as the oral pressure during [p]-occlusion by means of a thin plastic tube (inner diameter -~ 4 mm), mounted in the flow mask so that it reached the subject's oral cavity and attached to a pressure trans- ducer (Glottal Enterprises 162) (16). During the recording sessions the oral pressure signal was mon- itored on an oscilloscope screen (Gould 20 MHz oscilloscope OS300) by the experimenter. The oral flow was recorded by means of a Rothenberg flow mask (Glottal Enterprises). Flow calibration was re- alized by means of a flow meter (VEB Priifger~ite- Werk, Medingen, type TG06 Nr a64083) attached to a high-pressure air bottle provided with a pressure re- duction valve. All data were recorded on separate tracks of a TEAC multichannel FM DAT recorder (RD-200T PCM, Teac Corp., Japan). The calibra- tions of flow and pressure were recorded on the tape.

Analysis Figure 3 shows the various signals recorded for a

series produced at high F 0 in soft phonation. The to- tal range of variation of the signal representing LV was determined for each subject so that any values could be expressed as a percentage of this range. The second/pae:/syllable from each series was selected for analysis. It was typically produced at about 90% of the vital capacity, and was regarded as representa- tive of phonation at high LV. The syllable produced at 20% of the maximum lung volume used in that series was selected to represent phonation at low lung volume. Thus, we avoided extremely low LVs which might trigger atypical glottal behavior (17). To check if the data systematically varied with LV, we also analyzed one syllable, produced at about 40% of the maximum LV, in the series, i.e., close to REL.

All flow signals were inverse filtered using the Glottal Enterprises filter. Two filters were used, one for the first and one for the second formant. A ripple- free closed phase was used as the criterion for tuning the filters. Four male and 4 female subjects showed negative flow during the closed phase under at least some phonatory conditions. This probably reflected occasional incidences of leakage between the flow mask and the subject's face. To ensure reliable analysis material, these subjects were excluded from the investigation. The resulting flow glottogram from each of 24 (14 + 10) subjects' signals was digitized and recorded on a data file, using the SWELL com- puter program (18). Oral pressure was recorded on a different track of the same file.

The flow glottogram characteristics were determined from the middle part of the vowel, where traces of articulatory movement were absent. The following glottogram characteristics were measured: peak-to-peak flow amplitude, glottal leakage defined as the mean of the flow values appearing during the quasi-closed phase, duration of the quasi-closed phase, and period time (Fig. 4). Subglottal pressure and the associated values of abdominal wall expansion and relative LV were determined for all analyzed vowels.

In addition, some measures possibly reflecting glottal adduction were examined: (a) the closed quotient, calculated as the ratio duration of the quasi- closed phase to the period time (in %); (b) the rela-



A b d ~ ~

Aud io

Pressure

Flow

Syllables selected for analysis) 1]" ~ 90% 40% 20%

FIG. 3. Example of one series produced at high F 0 in soft phonation, showing the various signals analyzed.

Period time PtP Flow < r-

/ ~ Leak

FIG. 4. Illustration of the glottogram characteristics analyzed: peak-to-peak (PtP) flow, quasi-closed phase (QCLph), glottal leak, period time.



five glottal area, estimated as the ratio peak-to-peak flow amplitude to the square root of subglottal pressure; (c) H1-H2, the level difference between the first and second partials of the voice source as determined from spectrum analysis of the flow glottogram (19-21); (d) glottal permittance, i.e., the ratio peak- to-peak flow amplitude to subglottal pressure; and (e) glottal compliance, computed as the ratio between the flow contained in the flow pulse to subglottal pressure. These data were gathered for all pitch, loudness, and LV conditions.

The analyzed parameters were submitted to an analysis of variance. Each parameter was analyzed with a 3 3 2 2 ANOVA, with pitch (low, mid, high), loudness (soft, mid, high), and LV (low, high) as within-subject factors, and gender as a between- subject factor. Due to occurrence of single missing values in the analysis, the number of subjects in the statistical material varied between the parameters.

RESULTS

The subjects were instructed to expand their abdominal wall during inhalation. All subjects followed this instruction. The flow glottogram characteristics systematically varied with LV, such that values pertaining to 40% LV were in between those pertaining to 90% and 20% LV. Henceforth, only the glottogram characteristics observed under the two latter conditions will be compared, thus representing high and

low LV, respectively. Table 1 shows the effects of LV on the various voice parameters.

As can be seen from the scatter plot in Fig. 5, LV was found to consistently affect subglottal pressure. The plot compares subglottal pressures observed under the same phonatory conditions at low and high LV; the diagonal represents zero difference. As illustrated in Fig. 5, subjects tended to use a higher subglottal pressure in high than in low LV (average across gender = 11.7 and 9.1 cm H20). This result was statistically highly significant (F(1,22) = 85.7, P < .001]. Thus, these untrained subjects seemed to re- frain from muscular compensation of the changing elasticity forces resulting from the decrease of LV. A similar dependence was also observed for the peak- to-peak flow amplitude, the averages for high and low LV being 0.39 l/s and 0.30 l/s, respectively [F(1,20) = 56, P < .001] (Fig. 6). This may be a con- sequence of the changes in subglottal pressure.

Figure 7 shows the data of closed quotient. This quotient increases with increasing subglottal pressure, and subglottal pressure was higher at high than at low LVs. The closed quotient was still lower at high LV (average 30.7%) than at low LV (average 35.9%), thus suggesting a greater glottal abduction force component at high LV. This result was also statistically highly significant [F(1,20) = 22.55, P < .001]. Figure 8 shows the glottal leakage, i.e., the mean flow, during the quasi-closed phase. This parameter showed greater values at high (average 0.17

TABLE 1. Results of analysis of variance (repeated measures) of the effects of LV on various voice parameters; averages are across gender, pitch, and loudness conditions

Average

Parameter High LV Low LV df F P

Ps (cm H20) 11.72 9.07 (I,22) 85.69 .000

Peak-to-peak flow (l/s) 0.39 0.30 (1,20) 55.95 .000

Closed quotient (%) 30.72 35.87 (1,20) 22.55 .000

Leakage (l/s) 0.17 0.12 (I ,21) 10.29 .004

H l-H2 (dB) 11.27 10.62 (1,20) 4.20 .054

Est. area (arbitrary unit) 0.11 0.10 ( 1,20) 19.08 .000

Compliance (arbitrary unit) 0.09 0.07 (1,20) 2.45 .133

Permittance (arbitrary unit) 0.03 0.03 (1,20) 0. I 0 .753


30 Subglottal Pressure (cm H20 )

25


20 E "6 > o~ 15 C ::3

--I

0 ,u 10

0 0 5 10 15 20 25 30

High Lung Volume

FIG. 5. Scatterplot of subglottal pressure in cm H20. Each data point refers to a given pitch and loudness condition in one subject, compared between high and low LV. Black squares and gray circles refer to male and female subjects, respectively.

Closed Quotient (%) 100

80

E " 60

_~ e o~ 40 G

J ~ ~ L~~ ' r~" I

0 0 20 40 60 80 100

High Lung Volume

FIG. 7. Scatterplot of closed quotient in percent. Each data point refers to a given pitch and loudness condition in one subject, compared between high and low LV. Black squares and gray circles refer to male and female subjects, respectively.

Peak-to-Peak Flow (I/s) Glottal Leakage (I/s) 1,6 1

1,4 -

0,8 1,2

" " 0,6

== 0,8 =~ =, .~

0,6 ~o 0 ,4 -- I . J

o, 02L o " I

.1 0 0 0 0,2 0,4 0,6 0,8 1 1,2 1,4 1,6

High Lung Volume

FIG. 6. Scatterplot of peak-to-peak flow amplitudes in l/s. Each data point refers to a given pitch and loudness condition in one subject, compared between high and low lung volume. Black squares and gray circles refer to male and female subjects, respectively.

0 0,2 0,4 0,6 0,8 1

High Lung Volume

FIG. 8. Scatterplot of glottal leakage in Vs. Each data point refers to a given pitch and loudness condition in one subject, compared between high and low LV. Black squares and gray circles refer to male and female subjects, respectively.



I/s) than at low (average 0.12 I/s) LV [F(1,21) = 10.29, P = .004]. The estimated relative glottal area systematically varied with LV, implying that the glottal abduction force component was greater at high (average 0.11) than at low (average 0.10) LV [F(1,20) = 19.08, P < .001] (Fig. 9).

As pointed out by Klatt and Klatt (20) and later by Holmberg and coworkers (22), H1-H2, i.e., the level difference between the two lowest voice source ,spectrum partials, can be expected to reflect glottal abduction. The data showed the expected tendency; the average for high LV was 11.3 dB and the average for low LV was 10.6 dB. This tendency was almost strong enough to reach statistical significance [F(1,20) = 4.2, P = .054]. On the other hand, this comparison is somewhat risky, as the data points compared were mostly associated with different subglottal pressures. No effect of LV was observed on glottal compliance and permittance (P = .133 and P =.753, respectively).

The dependence of lung volume on pitch, loudness, and gender was analyzed. No significant within-subject effects were found for LV by pitch. For LV by loudness, the subglottal pressure and leakage pa-

Relative Estimated Glottal Area

4 f 0,3 !

I - J

o,1

0 0 0,1 0,2 0,3 0,4

High Lung Volume FIG. 9. Scatterplot of the relative estimated glottal area (peak- to-peak flow/square root of Ps) in an arbitrary unit. Each data point refers to a given pitch and loudness condition in one subject, compared between high and lowLV. Black squares and gray circles refer to male and female subjects, respectively.

rameters showed significant effects [F(2,44) = 7,41, P = .002 and F(2,42) = 5,57, P = .007, respectively]. Thus, the effect of LV on Ps was greatest in loud phonation and the effect of LV on leakage was greatest in soft phonation. The results of the various voice parameters' dependence on LV were similar for male and female subjects. However, the peak-to-peak airflow formed an exception; LV induced greater differ- ences in males than in females. The means for high and low LV were 0.51 and 0.39 l/s in male and 0.17 and 0.13 I/s in female subjects, respectively. Thus, the effect of LV on peak-to-peak airflow was greater in the male subjects [F(1,20) = 13,7, P = .001].

DISCUSSION

This attempt to quantitatively assess the significance of LV to glottal voice source characteristics has clearly demonstrated that respiratory factors do affect phonation. Thus, our investigation provides scientific support for the common experience in voice therapy and singing pedagogy that phonation can be improved by modifying phonatory breathing behavior.

Several significant phonatory effects of LV were observed in the present study. We found higher subglottal pressure, greater flow amplitude, a lower closed quotient, greater glottal leakage, and greater relative estimated glottal area at high as compared to low LV. In addition, we found an almost significantly greater difference between the two lowest voice source spectrum partials, H1-H2. It is well known that a variation in subglottal pressure affects many glottal parameters, other things being equal. For in- stance, flow amplitude tends to be small and glottal leakage tends to be large at low subglottal pressures compared to high subglottal pressures (13). Howev- er, in the present investigation, the glottal leakage was greater at high LV than at low LV, i.e., at high subglottal pressures than at low subglottal pressures. Likewise, closed quotient was clearly lower at high subglottal pressure than at low subglottal pressure. This suggests that the overall glottal abduction force is greater at high LVs than at low LVs.

Our results show that the transglottal airflow is likely to decrease with decreasing lung volume, other things being equal. Airflow also tends to decrease with decreasing subglottal pressure. Schneider and



Baken (23) observed that the correlation between mean airflow and intensity was significantly stronger in 10 vocally untrained male subjects when they performed a dimenuendo compared to when they performed a crescendo. The authors pointed out that a diminuendo task requires high subglottal pressure at the beginning of the exhalation, i.e., at high LV. Our results seem to explain this stronger relation; in a diminuendo, both the decreasing subglottal pressure and the decreasing LV will contribute to decreasing the airflow. In a crescendo, on the other hand, the airflow is affected in two opposite ways; the increasing subglottal pressure will tend to increase the airflow, while the decreasing LV will tend to decrease the airflow. A greater variability in the airflow-intensity relationship could therefore be expected in a crescendo than in a dimenuendo.

In our experiment all subjects expanded their abdominal wall when they inhaled, in accordance with the instructions. It is hard to decide to what extent the observed phonatory effects depended on the LV or on the expansion of the abdominal wall during inhalation. On the other hand, the behavior of the abdominal wall greatly varied between subjects when phonation was initiated. A crucial question seems to be if the same phonatory effects exist when inhalation is performed with a contracted abdominal wall.

Neither is it possible to decide if the phonatory effects were due to an abductive component of tracheal pull; this seems to be a strong possibility. Indeed, some major phonatory effects, such as the lower closed quotient, the greater glottal leakage, and H1-H2 observed at high LVs, are compatible with an abductive component of tracheal pull. On the other hand, the dependence of phonation on LV may em- anate not only from mechanical, but also from muscular factors, or from a combination of both. Bran- catisano et al. (10) studied the movements of the vocal folds during quiet breathing and found an abduction during inhalation and a movement toward the midline during expiration. The authors summa- rized that the relationship between the width of the glottic aperture and respiratory movements during quiet breathing points to a tight coupling between the motorneurons of the intrinsic laryngeal muscles and the respiratory center. Under conditions of quiet breathing the variation of glottal width has been as-

cribed to a modulation of the activity of the posterior cricoarytenoid muscle (PCA) (24). Taking into con- sideration the substantial difference in the glottal adjustment during quiet breathing and phonation, the question seems to remain: To what extent can findings made during quiet breathing be assumed to also apply to phonation, and in particular with regard to the roles played by mechanical and muscular forces?

We tried many glottogram measures to estimate the effects of LV on the glottal abduction forces: the estimated relative glottal area, the H1-H2 difference, the permittance, and the compliance. Of these, the first two mentioned reached and almost reached significance at the 95% level, respectively. It is hard to decide which of these alternatives best reflects the overall glottal adduction force. The problem with all of these measures is that they vary with subglottal pressure in a way that needs to be further elucidated.

Shipp and coworkers (17) estimated glottal adduction forces from electromyography (EMG) signals of laryngeal muscles measured at LV extremes. They examined the difference in the EMG amplitude from the adducting interarytenoid and the abducting posterior cricoarytenoid muscles and found that this difference was greater at maximum LV than at mini- mum LV, thus suggesting that adduction was greater at high LV. The present study revealed signs of a smaller adduction force at high LVs, i.e., the opposite result. On the other hand, our data concerned the overall output as manifested in terms of phonation, which can be assumed to reflect the summed effects of muscular and mechanical forces. In addition, Shipp et al. used highly trained singer subjects, whereas our subjects were all nonsingers. It seems reasonable to assume that singers more carefully compensate for changes of mechanical conditions than nonsingers. Our results lend support for the latter assumption in that our subjects did not fully compensate for the elasticity effects on subglottal pressure.

Our results seem to imply that LV affects glottal adduction. Some support for this idea can be found in the literature. Sperry and coworkers (25) observed that a female patient with a hyperfunctional voice and nodules tended to terminate her utterances at lower than normal LVs. Hoit and coworkers (26) claim that, "it may be that a modification as simple as initiating breath groups at higher lung volumes



could enhance voice quality and reduce the effort in- volved in country singing" (p48). Referring to Hixon and Putnam (27), Hoit et al. also point out that, "speaking at low lung volumes has been shown to be associated with functional misuse of the voice"(p49). The present investigation seems to offer a mechanical and/or physiological explanation for these obser- vations. Moreover, our findings suggest that the relation between LV and phonation might be taken "advantage of in voice therapy and singing pedagogy, particularly if phonatory behavior is taken into ac- count. Thus, hyperfunctional voices might profit from phonation at high LVs; while for hypofunctional voices, it may not be helpful to initiate phonation af- ter a deep inhalation. Similarly, our results seem to explain the typical experience in singing pedagogy that there is a great difference in the task of singing a descending scale as opposed to an ascending scale. In a descending scale an exaggerated adduction for the high notes is likely to be counteracted by the abductive component associated with the high LV.

CONCLUSIONS

This investigation has demonstrated that LV affects phonation, such that the overall glottal adduction seems smaller at high LVs than at low LVs. Thus, the investigation provides some quantitative support for the classical experience in voice therapy and singing pedagogy that breathing habits can be used as a means to modify phonation.

Acknowledgments: The subjects are acknowledged for their kind cooperation. Joakim Westerlund is gratefully ac-

knowledged for his help with the statistical analysis and

Peta White for checking the English. This investigation was

partly supported by the Swedish Research Council for En-

gineering Sciences and by a grant from Sven and Dagmar

Salrns Stiftelse. J. Iwarsson was also supported by grants

from Karolinska Institute and Committee for the Health

and Caring Sciences. J. Iwarsson carried out the inverse fil-

tering, analysed the flow glottograms and the pressure da-

m, and M. Thomasson analysed the respiratory data.

REFERENCES

1. Fritzell B. Voice disorders and occupation. Logoped Phoniatr Vocol 1996;21:7-12.

2. Hoit J, Solomon NP, Hixon T. Effect of lung volume on voice onset time (VOT). J Speech Heal" Res 1993;36:516-21.

3. Zenker W, Glaninger.l. Die Sttirke des Trachealzuges beim lebenden Menschen und seine Bedeutung ftir die Kehl- kopfmechanik. Z Biol 1959; 111 : 155-64.

4. Zenker W, Zenker A. Uber die Regelung der Stimmlip- penspannung durch von aussen eingreifende Mechanismen. Folia Phoniatr 1960; 12:1-36.

5. Zenker W. Questions regarding the function of external laryngeal muscles. In: Brewer D, ed. Research potentials h~ voice physiology. Syracuse, NY: State University of New York, 1964:20--40.

6. Vilkman E, Karma P. Vertical hyoid bone displacement and fundamental frequency of phonation. Acta Otolat3,ngol 1989;108:142-5 I.

7. Vilkman E, Sonninen A, Hurme P, K6rkk6 P. External laryngeal frame function in voice production revisited: a re- view. J Voice 1996;10:78-92.

8. Macklin C. X-ray studies on bronchial movements. Am J Anat 1925;35:303-20.

9. Fink BR, Demarest ILl. Lal3,ngeal biomechanics. Cam- bridge, MA: Harvard University Press, 1978:15--43.

10. Brancatisano T, Collett P W, Engel LA. Respiratory movements of the vocal cords. J Appl Physiol 1983;54:1269-76.

11. Stanescu DC, Pattijn J, Cl6ment J, van de Woestijne KP. Glottis opening and airway resistance. J Appl Physiol 1972; 32:460-6.

12. Titze IR. Talkin DT. A theoretical study of the effects of various laryngeal configurations on the acoustics of phonation. J Acoust Soc Am 1979;66:60-74.

13. Gauffin J, Sundberg J. Spectral correlates of glottal voice source waveform characteristics. J Speech Hear Res 1989: 32:556-65.

14. Sundberg J. Vocal fold vibration patterns and phonatory modes. Speech Transmission Laboratol 3, Quarterly progress and status report. Stockholm: Royal Institute of Technology, 1994;2-3:69-80.

15. Hixon TJ. Respiratory fimction hi speech and song. San Diego, Calif: Singular Publishing Group, 1991 : 1-54.

16. Hertegfird S, Gauffin J, Lindestad P,~. A comparison of subglottal and intraoral pressure measurement during phonation. J Voice 1995;9:149-55

17. Shipp T, Morissey P, Haglund S. Laryngeal muscle adjustment for sustained phonation at lung volume extremes. In: Askenfelt A, Felicetti S, Jansson E, Sundberg J, eds. Pro- ceedings of the Stockhohn Music Acoustics Conference 1983 (SMAC 83). Stockholm: Royal Swedish Academy of Music; 1985;46( 1 ):269-77.

18. Soundswell Signal Workstation [software]. Stockholm, Swe- den: AB Nyvalla DSP, 1996.

19. Bickley CA. Acoustic Analysis and Perception of Breathy Vowels. Speech communication group working papers. Cambridge, MA: Research Laboratory of Electronics, MIT;2:71-81.



20. Klatt DH, Klatt LC. Analysis, synthesis and perception of voice quality variation among female and male talkers. J Acoust Soc Am 1990;87:820--57.

21. Stevens K, Hanson H. Classification of glottal vibration from acoustic measurements. In: Fujimura O, Hirano M, eds. Vocal fold physiology: voice qualit3, control. San Diego, Calif: Singular Publishing Group, 1995:147-70.

22. Holmberg EB, Hillman, RE, Perkell, JS, Guiod PC, Gold- man SL. Comparisons among aerodynamic, electroglotto- graphic, and acoustic spectral measures of female voice. J Speech Hear" Res 1995;38:1212-23.

23. Schneider P, Baken RJ. Influence of lung volume on the airflow-intensity relationship. J Speech Hear Res 1984;27:430--5.

24. Brancatisano T, Dodd DS, Engel LA. Respiratory activity of posterior cricoarytenoid muscle and vocal cords in humans. J Appl Physiol 1984;56;1143-9.

25. Sperry E, Hillman RE, Perkell JS. The use of inductance plethysmography to assess respiratory function in a patient with vocal nodules. J Med Speech-Lang Pathol 1994;2: 137-45.

26. Hoit JD, Jenks CL, Watson P J, Cleveland TF. Respiratory function during speaking and singing in professional country singers. J Voice 1996;10:39-49

27. Hixon TJ, Putnam AHB. Voice abnormalities in relation to respiratory kinematics. Semin Speech Lang 1983;5(4): 217-31.


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