Lesya Chorna

Sentence intelligibility before and after voice treatment in speakers with idiopathic Parkinson's disease.

OBJECTIVES/HYPOTHESIS The purpose of this study was to determine whether sentence intelligibility improves in speakers with idiopathic Parkinsons disease (PD) as a result of Lee Silverman Voice Treatment (LSVT). It was hypothesized that all the speakers would improve following treatment, in association with increased vocal loudness, which was the primary target of the treatment. STUDY DESIGN Prospective study of eight Speakers with PD using a single-blinded, randomized pre-post treatment design, with multiple daily assessments before and after treatment was carried out. Resultant data were corrected for regression to the mean. METHODS Randomized digital recordings of sentences produced by speakers with idiopathic PD before and after the treatment were presented to normal-hearing listeners with equalized intensity at conversational loudness in the presence of pink noise. Percentage of words understood was calculated before and after the treatment. Changes in overall vocal intensity were also analyzed. RESULTS There was a statistically significant group effect from pre-to-post voice treatment; however, there was also significant interaction of treatment with speakers. Six of the speakers with PD improved significantly following voice treatment, one exhibited no change, and one exhibited a decline in sentence intelligibility post-treatment. CONCLUSIONS LSVT yielded significant improvement in sentence intelligibility for most speakers in the study but was not beneficial for two of the speakers despite the fact that they increased their overall vocal loudness.

Functional flexibility of infant vocalization and the emergence of language

We report on the emergence of functional flexibility in vocalizations of human infants. This vastly underappreciated capability becomes apparent when prelinguistic vocalizations express a full range of emotional content—positive, neutral, and negative. The data show that at least three types of infant vocalizations (squeals, vowel-like sounds, and growls) occur with this full range of expression by 3–4 mo of age. In contrast, infant cry and laughter, which are species-specific signals apparently homologous to vocal calls in other primates, show functional stability, with cry overwhelmingly expressing negative and laughter positive emotional states. Functional flexibility is a sine qua non in spoken language, because all words or sentences can be produced as expressions of varying emotional states and because learning conventional “meanings” requires the ability to produce sounds that are free of any predetermined function. Functional flexibility is a defining characteristic of language, and empirically it appears before syntax, word learning, and even earlier-developing features presumed to be critical to language (e.g., joint attention, syllable imitation, and canonical babbling). The appearance of functional flexibility early in the first year of human life is a critical step in the development of vocal language and may have been a critical step in the evolution of human language, preceding protosyntax and even primitive single words. Such flexible affect expression of vocalizations has not yet been reported for any nonhuman primate but if found to occur would suggest deep roots for functional flexibility of vocalization in our primate heritage.

Vocal aging and adductor spasmodic dysphonia: response to botulinum toxin injection.

Aging of the larynx is characterized by involutional changes which alter its biomechanical and neural properties and create a biological environment that is different from younger counterparts. Illustrative anatomical examples are presented. This natural, non-disease process appears to set conditions which may influence the effectiveness of botulinum toxin injection and our expectations for its success. Adductor spasmodic dysphonia, a type of laryngeal dystonia, is typically treated using botulinum toxin injections of the vocal folds in order to suppress adductory muscle spasms which are disruptive to production of speech and voice. A few studies have suggested diminished response to treatment in older patients with adductor spasmodic dysphonia. This retrospective study provides a reanalysis of existing pre-to-post treatment data as function of age. Perceptual judgments of speech produced by 42 patients with ADSD were made by two panels of professional listeners with expertise in voice or fluency of speech. Results demonstrate a markedly reduced positive response to botulinum toxin treatment in the older patients. Perceptual findings are further elucidated by means of acoustic spectrography. Literature on vocal aging is reviewed to provide a specific set of biological mechanisms that best account for the observed interaction of botulinum toxin treatment with advancing age.

Acoustic Measures of Phonation during Connected Speech in Adductor Spasmodic Dysphonia

Objectives: This study examined acoustic measures related to voice production in connected speech of patients with adductor spasmodic dysphonia (ADSD) before and after boltulinum toxin (BT) treatment in comparison with speech of non-dysphonic healthy control (NHC) speakers. Correlations between acoustic measures and perceptual scaling judgments of overall voice quality were also examined. Methods: Ten patients with moderate-to-severe ADSD were audio-recorded prior to and following BT injection, as were age and gender matched NHCs. Signal processing algorithms were employed to extract fundamental frequency (f 0 ) and intensity (dB) of speakers’ digitized oral readings. Control procedures minimized the influence of severely aperiodic phonation and obstruent consonant production on the analysis of modal f 0 and related variables such as signal-to-noise ratio (SNR). Measures of severe aperiodicity, with f 0 < 80 Hz, were compared with modal f 0 data. Perceptual judgments of voice quality were obtained from expert voice clinicians under rigorously controlled listening conditions. Results: Acoustic measures of number of low frequency f 0 events, coefficient of variation of modal f 0 , and SNR demonstrated statistically significant differences for ADSD speech before and after treatment, and differentiated between ADSD and NHC speakers. Mean modal f 0 did not differentiate among speaker conditions. All other measures differentiated untreated ADSD speech from that of NHCs; however, only selected measures demonstrated differences between NHC and ADSD speakers following BT injection. Coefficient of variation of modal f 0 and SNR were moderately correlated with expert listener judgments of voice quality. Conclusion: Acoustic measures of connected speech derived from carefully edited modal f 0 tracks and intensity contours were effective for characterizing ADSD speech before and after treatment, and for differentiating it from that of NHCs. Acoustic measures were highly reliable and significantly related to voice quality scaling by expert listeners.