Acoustic voice analysis in untreated patients with Parkinson's disease

To quantify several acoustic features of the voice in patients with Parkinson's disease (PD) not treated with dopaminergic drugs, 22 PD patients and 28 age and sex-matched controls were studied. The Computerized Speech Lab 4300 program (Kay Elemetrics) was used. Two seconds of a sustained /a/ and a sentence were captured with a microphone and laryngograph equipment. Measures included fundamental frequency (F(0)), frequency perturbation (jitter), intensity perturbation (shimmer), and harmonic/noise ratio (HIN) of the vowel /a/, and frequency and intensity variability of a sentence, phonational range, dynamic range at the natural frequency, maximum phonational time and s z ratio. All subjects underwent indirect laryngoscopy and/or laryngeal fibroscopy. When compared to controls, PD patients showed higher jitter and shimmer, lower H N ratio, and lower frequency variability of the sentence in the microphonic signal and reported a higher frequency of presence of low voice intensity, monopitch, harshness, voice arrests, and tremor.