Acoustic measurement of voice quality in central dysphonia.

Speech samples of 14 male and 10 female patients with central dysphonia were examined. Eighteen patients had suffered a severe closed head trauma and the remaining six patients had experienced cerebrovascular accident (CVA). Several parameters were developed in order to find acoustic correlates for three major pathologic voice qualities in central dysphonia. The well know jitter parameter, fundamental period perturbation (PP), was adapted for our purposes and proved to be a good measure for rough voices, though the patients revealed less jitter than in peripheral dysphonia. The vocal onset parameter, time lag of preexhalation (Tb), and the spectral parameter, spectral energy above 5 KHz (A5), classified the breathy voices. Most of the tense voices could be detected by the spectral parameters, spectral energy in the 1-5 KHz range (A1), and variance of spectral energy above 5 KHz (V5). The successful classification of these voice qualities allowed the description of compound pathologic voice types in central dysphonia.