VARIATIONS IN ADDUCTOR SPASMODIC DYSPHONIA - ACOUSTIC EVIDENCE

Acoustic analysis was used to gain information about the normal, as we ll as the abnormal acoustic events associated with adductor spasmodic dysphonia (ADSD). This analysis was completed to determine whether spe cific acoustic events could be used to differentiate the voice of indi viduals with ADSD from those with normal voice. A group comparison bet ween 14 women diagnosed with ADSD and 14 women (age-matched) with no e vidence of vocal pathology or vocal dysfunction was completed. Phonato ry breaks, aperiodicity, and frequency shifts, acoustic parameters pre viously identified in ADSD, were found throughout sustained vowel prod uctions. The duration of the phonatory breaks and aperiodic segments w as calculated and the amount of frequency shift was determined. The lo cation of each acoustic event was marked relative to the onset of the vowel production. The subjects with ADSD presented with normal phonati on and various amounts of each of the three acoustic parameters. Aperi odic segments primarily characterized the phonation of ADSD, followed by frequency shifts and phonatory breaks. The location of each of thes e acoustic events was within the midportion of the vowel production. T he advantages of segmenting the acoustic waveform into these measures and separating the spasmodic events from normal phonation when examini ng laryngeal motor control of spasmodic dysphonics is discussed.