BALBUZIE e LARINGOSPASMO – Evidence of laryngeal blocks in acoustic analysis of stuttered speech

Un ricerca acustica presso l’Universita di Toledo – Dipartimento di riabilitazione, presentata The Second Pan-American/Iberian Meeting on Acoustics  Cancun, Mexico (15–19 November 2010) ha evidenziato un blocco nella regione delle corde vocali. L’esame, effettuato per mezzo del sonografo, ha analizzato acusticamente l’eloquio di un soggetto affetto da grave balbuzie,  sia durante compiti di lettura che durante il discorso spontaneo. Gli studiosi sono in attesa di una successiva ricerca i follow-up che analizzi il ciclo della glottide.
Ricordiamo come Il Dottor Martin F. Schwartz, direttore del National Center for Stuttering (USA) nel lontano 1974 indicò nel laringospasmo  scoprì la causa fisica della balbuzie; da queste indagini nasce la “tecnica del flusso d’aria passivo”, ancor oggi alla base di molti metodi per il controllo della balbuzie.

J. Acoust. Soc. Am. Volume 128, Issue 4, pp. 2290-2290 (2010); (1 page) – Caroline Menezes, Chelsea Dowler, and Lee Ellis – Dept. of Rehabilitation Sci., Univ. of Toledo, 2801 W. Bancroft St., Toledo, OH 43606

Stuttered speech is characterized by the presence of speech blocks. Little is known on what causes blocks. These blocks typically occur on onset segments of a syllable regardless of the number of syllables in the stuttered word. Blocks on voiced and voiceless stops often result in part word repetitions (e.g., c c c car), while fricatives and other + continuant sounds will be prolonged. Therefore, the manner of sound production plays a role in identifying the types of blocks that will occur. Preliminary acoustic analysis of the speech of one subject with severe stuttering reveals that blocks occurring on voiced +continuant segments are prolonged; however, there is partial or complete devoicing of the voiced segment associated with the block. Devoicing is evident in the spectrogram by the absence of voicing bar and fundamental frequency. Sonorant segments can be identified by their resonant frequencies. This pattern was found in both spontaneous and read speech. The presence of resonant frequencies in the absence of a fundamental frequency indicates a block at the region of the vocal folds. A follow up to this study analyzing simultaneous EGG and acoustic recordings to look at the glottal cycle during stuttered blocks is required.

© 2010 Acoustical Society of America

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