Acoustic and Respiratory Characteristics of Infant Vocalization

The purpose of this dissertation was to explore vibratory regime of infant phonation. The first study examined 1) differences in overall levels of acoustic and respiratory variables between different regimes and 2) differences in relationships between the acoustic and respiratory variables among regimes. The second study examined 3) the acoustic and respiratory ranges of modal phonation with respect to other regimes and 4) the range of modal phonation among infants of different ages. Two datasets were used in the study. Dataset I was acquired from eight infants of ages 8-18 months, and Dataset II from one infant of ages 4-6 months. Their vocalizations and respiratory movements were recorded during adult-interaction. Phonated segments were identified through waveform, spectrogram, and auditory inspection, and categorized into six mutually exclusive regimes (modal, pulse, loft, subharmonics, biphonation, and chaos). For each regime segment, the following measurements were made: fundamental frequency (F0), sound pressure level (SPL), expiratory slope, and relative lung volume at regime initiation. A series of linear mixed-effects model analysis and analysis of variance revealed differences in mean F0 between regimes, mean SPL, and mean. Correlations between the acoustic and respiratory variables differed among regimes, indicating their relationships were regime-dependent. The most revealing findings were that regime categories readily distributed into different regions of the intensity-frequency space, and that F0 ranges of modal regime tended to decrease with increasing age. In addition to modal, pulse, and loft distributing around the mid, low, and high intensity-frequency regions, respectively, biphonation and subharmonics were found between modal and loft ranges. The upper end of F0 range for pulse was much higher in infants compared to adults, however, biphonation and subharmonics rarely occurred between pulse and modal ranges. A range of modal F0 was about 500 Hz for the young infant in the vocal expansion stage, and about 200 Hz for older infants in the (post-)canonical stage. Although the results are tentative, this finding suggests that F0 variability decreases with age and phonation becomes more restricted to a lower end of an F0 range

Perceptual structure of adductor spasmodic dysphonia and its acoustic correlates

OBJECTIVES: To examine the perceptual structure of voice attributes in adductor spasmodic dysphonia (ADSD) before and after botulinum toxin treatment and identify acoustic correlates of underlying perceptual factors. Reliability of perceptual judgments is considered in detail. STUDY DESIGN: Pre- and posttreatment trial with comparison to healthy controls, using single-blind randomized listener judgments of voice qualities, as well as retrospective comparison with acoustic measurements. METHODS: Oral readings were recorded from 42 ADSD speakers before and after treatment as well as from their age- and sex-matched controls. Experienced judges listened to speech samples and rated attributes of overall voice quality, breathiness, roughness, and brokenness, using computer-implemented visual analog scaling. Data were adjusted for regression to the mean and submitted to principal components factor analysis. Acoustic waveforms, extracted from the reading samples, were analyzed and measurements correlated with perceptual factor scores. RESULTS: Four reliable perceptual variables of ADSD voice were effectively reduced to two underlying factors that corresponded to hyperadduction, most strongly associated with roughness, and hypoadduction, most strongly associated with breathiness. After treatment, the hyperadduction factor improved, whereas the hypoadduction factor worsened. Statistically significant (P\u3c0.01) correlations were observed between perceived roughness and four acoustic measures, whereas breathiness correlated with aperiodicity and cepstral peak prominence (CPPs). CONCLUSIONS: This study supported a two-factor model of ADSD, suggesting perceptual characterization by both hyperadduction and hypoadduction before and after treatment. Responses of the factors to treatment were consistent with previous research. Correlations among perceptual and acoustic variables suggested that multiple acoustic features contributed to the overall impression of roughness. Although CPPs appears to be a partial correlate of perceived breathiness, a physical basis of this percept remained less clear

Analyzing journal abstracts written by Japanese, American, and British scientists using Coh-Metrix and the Gramulator

This interdisciplinary study comprises two complementary analyses on a corpus of journal abstracts written in English by American, British, and Japanese scientists. The fi rst analysis uses the computational tool Coh-Metrix to assess text at the discourse level. The second analysis uses the computational tool the Gramulator to compare the frequency of n-grams across the three sources of abstracts. The Coh-Metrix and Gramulator analyses both suggest signifi cant differences between all three varieties of English. The greatest differences were apparent when comparing abstracts written by Japanese and English speakers; however, a number of differences were also apparent when comparing the British English and American English varieties. The results lend weight to the conclusion that native-English speakers (reviewer, editor, or reader) of either the British or American variety may interpret Japanese-English texts as lacking in key areas of the proto-typical style of the English register. Our findings provide information for instructors, course developers, and scientists on how and where text might be modifi ed in order to facilitate the production of more native-English-like representations