Influence of mean sound pressure level on jitter and shimmer measures

The sound of senescence

This paper draws together findings of recent studies examining changes in voice with aging. Listeners' accuracy in perceiving age from voice is discussed, along with changes in speaking fundamental frequency, fundamental frequency stability, temporal aspects of speech, and resonance features of voice with aging. Descriptions are provided of differences in glottal gap configuration as a function of age and gender. In addition, acoustic/temporal measures that have been demonstrated to correlate with perceived age estimates are presented.

Intrasubject variability of objective voice measures

Recent advances in the diagnosis and treatment of voice disorders necessitate the need for accurate and reliable objective voice measurements. There are many instruments commonly used to analyze voice data. Many, if not most, of these instruments have not been adequately tested for reliability or consistency. This study evaluates the intrasubject variability of the objective voice measurements from two commonly used voice analysis instruments. The study also presents data correlating subjective mood states, room temperatures, sleep times of the subject, time since last meal, and hydration levels to the various acoustic measures. Several weak but significant correlations were obtained and are discussed. Guidelines for the appropriate use of these instruments are described.

Fo-perturbation and Fo/loudness dynamics in voices of normal children, with and without education in singing

Sustained phonations were compared in two groups of children (aged 7-12), one with special artistic voice education and one from a normal school, without voice complaints or problems. The hypothesis of specific (better) biomechanical vocal fold properties in the first group is confronted with the hypothesis of differences solely related to training of voice control. In both groups, Fo-aperiodicity was measured in a sustained phonation at 3 different SPL levels. As a general rule, aperiodicity clearly decreases when the voice becomes louder. Aperiodicity is highly significantly lower, at all SPL-levels, in children with trained singing voices: this implies better mechanical properties of the vocal oscillator. The Fo/SPL relation on a sustained /a:/ does not differ in trained and untrained children's voices: out of singing context, trained children do not spontaneously control the Fo/SPL dynamics differently from untrained children. The higher regularity of vocal fold pulses is not related to the duration of training.

Fundamental frequency, intensity, and vowel selection: effects on measures of phonatory stability

Measures of phonatory stability such as jitter, shimmer, and signal-to-noise ratio (SNR) are increasingly used in clinics and laboratories, yet questions about the effects of various aspects of voice production on these acoustic variables have received only limited attention. The purpose of the present study was to examine the effects of frequency, intensity, and vowel selection on those measures of phonatory stability. Twenty-nine young adult females were used as subjects. Each subject produced vocalizations at her speaking fundamental frequency (SFF) and one octave above SFF; at 60, 70, and 80 dB; and on the vowels /i/ and /a/, for a total of 12 vocalizations per subject. These vocalizations were then analyzed, using CSpeech acoustic analysis software, to obtain measures of jitter, shimmer, and SNR. Results revealed that frequency, intensity, and vowel selection all affected various phonatory stability measures, with the highest perturbation values almost always occurring in the low frequency-low intensity condition. Implications and physiological explanations for the results of the study were presented.

Phonatory and articulatory changes associated with increased vocal intensity in Parkinson disease: a case study

This study examined changes in voice and speech production in a patient with Parkinson disease as he increased vocal intensity following 1 month of intensive voice treatment. Phonatory function and articulatory acoustic measures were made before and after treatment as well as 6 and 12 months later. Pre- to post-treatment increases were documented in sound pressure level in sustained phonation, syllable repetition, reading, and monologue. Consistent with mechanisms of intensity change reported in normal speakers, corresponding improvements were measured in estimated subglottal pressure, maximum flow declination rate, laryngeal airway resistance, open quotient, EGGW-25, harmonic-spectral slope, and maximum vowel duration. Measures of phonatory stability in sustained phonation and semitone standard deviation in reading and speaking showed changes accompanying increased vocal intensity. In addition, changes were measured in articulatory acoustic parameters (vowel and whole word duration, transition duration, extent and rate, and frication duration and rise time) in single-word productions. These findings indicate that this patient increased his vocal intensity using phonatory mechanisms that have been associated with the nondisordered larynx. In addition, the increased vocal intensity led to changes in articulation that were not targeted in treatment.

Vocal stability and vocal tract configuration: an acoustic and electroglottographic investigation

Previous studies have reported differences in vocal fundamental frequency perturbation (jitter) and amplitude perturbation (shimmer) measures as a function of vowel type. However, it is not clear from those studies whether these effects derive from modifications in the shape of the vocal tract or from intrinsic vowel differences in mean fundamental frequency and vocal amplitude. The present study sought to address this issue using simultaneously obtained acoustic and electroglottographic (EGG) signals. Ten normal adult men and 10 normal adult women prolonged three maximally stable productions of the vowels [symbol: see text]. Vocal sound pressure level was maintained at 74 +/- 4 dB, while mean fundamental frequency was maintained at 110 and 220 Hz +/- 0.5 st for the male and female subjects, respectively. Results indicated that when vocal frequency and intensity are controlled, acoustic and EGG measures of mean jitter and shimmer do not show a significant vowel effect.

Articulatory, developmental, and gender effects on measures of fundamental frequency and jitter

Fundamental frequency (Fo) and jitter were measured in digitized live-voice productions of sustained vowels [a], [i], and [u] from women, men, and 6- through 9-year-old children. Results showed (a) significant developmental differences for mean Fo and for the pattern of jitter by vowel type, (b) significant gender differences in Fo and jitter only for adults, (c) significant differences in Fo and jitter according to vowel type for all subjects, and (d) similar amounts of mean absolute jitter for children and women for all vowels with nonsignificantly different values of jitter for boys and men on [i] and [u] productions. Results are related to Honda's theory of intrinsic Fo for vowels and to Titze's neurologic model of jitter.