John H. Saxman

Vocal fundamental frequency characteristics during the first two years of life

Vocal fundamental frequency (Fo) characteristics were sampled for a group of seven young children. The children were followed longitudinally for a 12-month period, spanning preword, single-word, and multiword vocalizations. The Fo characteristics were analyzed with reference to chronological age, vocalization length, and lexicon size. Measures of average Fo and Fo variability changed little during the 12-month period for each child. A rising-falling intonation contour was the most prevalent Fo contour among the children. In general, the influence of vocalization length and language acquisition on measures of Fo was negligible. It is suggested that relative uniformity in vocal Fo exists in early vocalizations across preword and meaningful speech periods.

Acoustic observations in young children’s non‐cry vocalizations

A corpus of 1200 non-cry vocalization samples produced by 14 normal children between the ages of 11-25 months was examined retrospectively. Six percent of the samples yielded instances of either harmonic doubling (HD), fundamental frequency (F0) shift, or biphonation (Bp). These spectrographic features relate to short duration changes in F0, reflecting alterations in vocal fold state characteristics. The HD and Bp segments were perceptually judged to be harsh, while F0 shift closely reflected pitch breaks. The frequency of occurrence of the three acoustic features suggests that they are normally occurring phonatory events in normal childrens vocal patterns.

Inverse-filtered air flow and EGG measures for sustained vowels and syllables***

The purpose of this investigation was to compare the effects of two speaking tasks on laryngeal measures obtained from inverse-filtered air flow and electroglottograph (EGG) waveforms. Flow amplitude, air flow duty cycle, EGG duty cycle, and fundamental frequency were measured for normal young and aged adults during vowel prolongation and syllable repetition. There were significant between-task differences for flow amplitude and fundamental frequency. Variability appeared no greater for syllable repetition than vowel prolongations. Syllable repetition was slightly better than vowel prolongation for differentiating the vocal behaviors of aged and young speakers. Between-task relationships were strong for fundamental frequency and more moderate for the other laryngeal measures. It was concluded that syllable repetition would be preferable to vowel prolongation for measurement of aerodynamic and EGG parameters and that findings could be generalized across speaking tasks for fundamental frequency but not air flow and duty cycle measures.

Acoustic features of normal-hearing pre-term infant cry

Acoustic features of expiratory cry vocalizations were studied in 125 pre-term infants prior to being discharged from a level-3 neonatal intensive care unit. The purpose was to describe various phonatory behaviors in infants in whom significant hearing loss could be ruled out. We also compared these results with normal-hearing full-term infants, and evaluated whether linkage exists among acoustic cry features and various anthropometric, diagnostic and treatment variables obtained throughout the peri- and neonatal periods. Our analysis revealed that cry duration was significantly related to total days receiving respiratory assistance. The occurrence of other complex spectral and temporal aspects of acoustic cry vocalizations including harmonic doubling and vibrato also increased in infants receiving some form of respiratory assistance. The presence of harmonic doubling also depended on weight and conceptional age at test. The discussion focuses on the implication of these relationships and directions for future research.

A comparison of intrasubject variation across sessions of three vocal frequency perturbation indices

Within-subject variation of three vocal frequency perturbation indices was compared across multiple sessions. The magnitude of jitter factor (JF), pitch perturbation quotient (PPQ), and directional perturbation quotient (DPF) was measured every other day for 33 consecutive days for ten female and five male normal young adult speakers. Perturbation measures were calculated using a zero-crossing analysis of taped [i] and [u] productions. Pearson product-moment correlations among the three perturbation indices were calculated to examine their relation over time. Coefficients of variation for JF, PPQ, and DPF were considered indicative of the temporal stability of the three measures. JF and PPQ provided redundant information about laryngeal behaviors in steady-state productions. DPF, however, appeared to measure different laryngeal behaviors. Also, JF and PPQ varied considerably within individuals across sessions while DPF was the more temporally stable measure. Multiple sampling sessions and measurement of both the magnitude and direction of period differences are advised for future investigations of vocal frequency perturbation.

A comparison of sung and spoken phonation onset gestures using high-speed digital imaging.

Phonation onset is important in the maintenance of healthy vocal production for speech and singing. The purpose of this preliminary study was to examine differences in vocal fold vibratory behavior between sung and spoken phonation onset gestures. Given the greater degree of precision required for the abrupt onset sung gestures, we hypothesize that differences exist in the timing and coordination of the vocal fold adductory gesture with the onset of vocal fold vibration. Staccato and German (a modified glottal plosive, so named for its occurrence in German classical singing) onset gestures were compared with breathy, normal, and hard onset gestures, using high-speed digital imaging. Samples were obtained from two subjects with no history of voice disorders (a female trained singer and a male nonsinger). Simultaneous capture of acoustical data confirmed the distinction among gestures. Image data were compared for glottal area configurations, degree of adductory positioning, number of small-amplitude prephonatory oscillations (PPOs), and timing of onset gesture events, the latter marked by maximum vocal fold abduction, maximum adduction, beginning of PPOs, and beginning of steady-state oscillation. Results reveal closer adductory positioning of the vocal folds for the staccato and German gestures. The data also suggest a direct relationship between the degree of adductory positioning and the number of PPOs. Results for the timing of onset gesture events suggest a relationship between discrete adductory positioning and more evenly spaced PPOs. By contrast, the overlapping of prephonatory adductory positioning with vibration onset revealed more unevenly spaced PPOs. This may support an existing hypothesis that less well-defined boundaries interfere with normal modes of vibration of the vocal fold tissue.

Fundamental frequency contours of preword vocalizations through the emergence of word combinations

An increasing number of acoustic characteristics of infant preword vocalizations have been found to be similar in many respects to the vocalization characteristics of childrens early meaningful speech. Such findings are suggestive of continuity in the underlying processes involved in acquiring language. To date, few studies exist that have examined in detail the acoustic characteristics of babbling, early words, and word combinations in a single group of children. The present study provides monthly data on fundamental frequency (F0) contours in seven infants who were audio tape recorded over a 12‐month period. Within a years time, each childs communication development progressed from babbling vocalizations to word combinations. The frequency and type of F0 contours in each childs mono‐, bi‐, and polysyllabic vocalizations are reported. Regardless of syllable type, the children used a large number of rising‐falling F0 contours across preword and multiword periods of vocalization development. The least ...

The Use of Learning Rate, Recall and Listener Confidence Ratings To Assess Effects of Acoustically Distorted Speech Stimuli

The present investigation was concerned with the application of three listener performance tasks; learning rate, recall, and listener confidence ratings as criteria for evaluating speech communication systems. Lists of 24 words, equal in intelligibility and content but differing in acoustic quality were presented auditorily to five groups of listeners. Both learning rate and the listener confidence ratings varied systematically with the type and severity of signal distortion. The results indicated that learning rate and listener confidence ratings are sensitive to signal distortion and may prove useful as criteria for assessing speech communication systems.