Eva B. Holmberg

Glottal airflow and transglottal air pressure measurements for male and female speakers in low, normal, and high pitch

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 (F 0 ). 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 F 0 from normal pitch.

Aerodynamic and acoustic voice measurements of patients with vocal nodules: variation in baseline and changes across voice therapy.

An important clinical issue concerns the efficacy of current voice therapy approaches in treating voice disorders, such as vocal nodules. Much research focuses on finding reliable methods for documentation of treatment results. In this second treatment study of ten patients with vocal nodules, who participated in a behaviorally based voice therapy program, 11 aerodynamic (transglottal air pressure and glottal waveform) and acoustic (spl, f0, and spectrum slope) measures were used. Three pretherapy baseline assessments were carried out, followed by one assessment after each of five therapy phases. Measurements were made of two types of speech materials: Strings of repeated /pae/ syllables and sustained /ae/ phonations in two loudness conditions: comfortable loudness and loud voice. The data were normalized using z-scores, which were based on data from 22 normal subjects. The results showed that the aerodynamic measures reflected the presence of vocal pathology to a higher degree than did the acoustic spectral measures, and they should be useful in studies comparing nodule and normal voice production. Large individual session-to-session variation was found for all measures across pretherapy baseline recordings, which contributed to nonsignificant differences between baseline and therapy data.

Phonatory function associated with hyperfunctionally related vocal fold lesions

Summary A combination of noninvasive acoustic and aerodynamic measures were used to compare and contrast vocal function among patients having one of four major types of hyperfunctionally related vocal fold lesions: nodules, polyps, polypoid degeneration, or contact ulcers. Measures included: (a) vocal intensity and fundamental frequency, (b) parameters derived from inverse filtered approximations of the glottal airflow waveform and (c) estimates of transglottal pressure and average glottal airflow. Preliminary results showed that a combination of measures of fundamental frequency, transglottal pressure, and maximum declination rate of the glottal airflow waveform appeared to differentiate among three of the different types of lesions studied (nodules, polypoid degeneration, and contact ulcers). These results were interpreted as evidence that different underlying phonatory mechanisms are associated with different types of hyperfunctionally related vocal fold lesions.

Stress, Anxiety, Somatic Complaints, and Voice Use in Women With Vocal NodulesPreliminary Findings

Psychosocial factors long have been associated with the development of hyperfunctional voice disorders such as vocal nodules. However, experimental evidence concerning the role of these factors in ...

Group differences in measures of voice production and revised values of maximum airflow declination rate

In previous reports, aerodynamic and acoustic measures of voice production were presented for groups of normal male and female speakers [Holmberg et al., J. Acoust. Soc. Am. 84, 511-529 (1988); J. Voice 3, 294-305 (1989)] that were used as norms in studies of voice disorders [Hillman et al., J. Speech Hear. Res. 32, 373-392 (1989); J. Voice 4, 52-63 (1990)]. Several of the measures were extracted from glottal airflow waveforms that were derived by inverse filtering a high-time-resolution oral airflow signal. Recently, the methods have been updated and a new study of additional subjects has been conducted. This report presents previous (1988) and current (1993) group mean values of sound pressure level, fundamental frequency, maximum airflow declination rate, ac flow, peak flow, minimum flow, ac-dc ratio, inferred subglottal air pressure, average flow, and glottal resistance. Statistical tests indicate overall group differences and differences for values of several individual parameters between the 1988 and 1993 studies. Some inter-study differences in parameter values may be due to sampling effects and minor methodological differences; however, a comparative test of 1988 and 1993 inverse filtering algorithms shows that some lower 1988 values of maximum flow declination rate were due at least in part to excessive low-pass filtering in the 1988 algorithm. The observed differences should have had a negligible influence on the conclusions of our studies of voice disorders.

A system for signal processing and data extraction from aerodynamic, acoustic, and electroglottographic signals in the study of voice production

A software system, implemented in the MITSYN languages, is described for signal processing and data extraction from oral airflow, intra-oral air pressure, vocal fold contact area (EGG) and sound pressure signals. Signal processing algorithms are specified in the form of block diagrams; examples are shown for demultiplexing signals into bandwidth-specific, time-aligned signal stream files and for inverse filtering the oral airflow waveform to obtain an approximation of the glottal airflow waveform. Interactive and algorithmic data extraction is performed with a menu-driven procedure that displays the stages of analysis, graphical indications of the results of algorithmically made decisions, and derived results. The system has proven to be useful for obtaining quantities of detailed data on voice production.

Individual Variation in Measures of Voice

Measures of inferred subglottal air pressure, glottal airflow waveform characteristics, sound pressure level (SPL) and the acoustic spectral slope were studied for individual speakers with normal voices. Combinations of different levels of subglottal air pressure and varying glottal configurations could result in the same SPL. Relatively high air pressure levels were associated with a steep spectral slope, reflecting a more sinusoidal glottal waveform and a relatively abducted membranous glottis, which would result in damping of F1. Data suggested that the interarytenoid glottal opening could vary without systematically affecting SPL or voice quality. The results indicate that the principles of production-related economy of effort and physiological, acoustic and perceptual constraints may apply to voice production.

Methods for using a noninvasive technique for estimating glottal functions from oral measurements

A noninvasive technique is used to make acoustic and aerodynamic recordings in an ongoing study whose goal is the objective assessment of vocal function in normal and dysphonic speakers. Intraoral pressure, oral volume velocity (flow), and radiated sound pressure are recorded for strings of repeated productions of the syllable /pae/. A high time resolution pneumothachograph is used to record flow [M. Rothenberg, J. Acoust. Soc. Am. 53, 1632–1645 (1973)]. Transglottal air pressure, glottal air flow, and sound power for the vowel are estimated from the oral measurements, and glottal resistance and vocal efficiency are calculated. Initial results suggest that production mode (smooth versus interrupted) and rate (slow versus fast) may affect the reliability of the aerodynamic measures. An interaction between production mode and rate can result in unreliable pressures on one hand and unreliable flows on the other. Results from a separate, methodological study illustrate the importance of control over productio...

Discriminating speakers with vocal nodules using aerodynamic and acoustic features

This paper demonstrates that linear discriminant analysis using aerodynamic and acoustic features is effective in discriminating speakers with vocal-fold nodules from normal speakers. Simultaneous aerodynamic and acoustic measurements of vocal function were taken of 14 women with bilateral vocal-fold nodules and 12 women with normal voice production. Features were extracted from the glottal airflow waveform and peaks in the acoustic spectrum for the vowel /ae/. Results show that the subglottal pressure, air flow, and open quotient are increased in the nodules group. Estimated first-formant bandwidths are increased, but result in minimal change in the first-formant amplitudes. There is no appreciable decrease in high frequency energy. Speakers with nodules may be compensating for the nodules by increasing the subglottal pressure, resulting in relatively good acoustics but increased air flows. The two best features for discrimination are open quotient and subglottal pressure.

Laryngeal airway resistance as a function of phonation type

An indirect method to estimate laryngeal airway resistance was investigated. The ratio of the intraoral pressure (IOP) for the voiceless stop and the volume velocity air flow (V0) for the open vowel in the CV utterance /pa/ was suggested to give an estimate of the laryngeal airway resistance (Rlaw); Rlaw = IOP/V0. The primary variable was phonation type. It was hypothesized that the Rlaw value would reflect the laryngeal airway resistance during: (1) normal, (2) pressed, and (3) breathy phonation. Other controlled variables were intensity and fundamental frequency. The results suggested that the Rlaw value was highest for pressed phonation and lowest for breathy phonation irrespective of intensity and fundamental frequency. Good discrimination in the Rlaw value between high and low intensity was also found. These results were interpreted to give evidence that the Rlaw value obtained with this method was a good index of actual resistance.