Effect of louder voicing on acoustical measurements in dysphonic patients

Abstract

Practically nothing is known about the possible effect of a slightly louder phonation (as reflected by the sound pressure level) on commonly used acoustical parameters for evaluation of pathological voice quality. In this experiment, 87 patients with various kinds of voice pathology produced a /a:/ firstly at comfortable pitch and loudness, and secondly a little louder (average SPL increase: 2,6 dB). In case of normal vocal fold anatomy or superficial vocal fold pathology (epithelium or Reinke's space), louder voicing significantly reduces the perturbation parameters (jitter and shimmer), and thus also the noise to harmonics ratio. This is probably due to the increase of the oscillating mass by larger involvement of normal deeper layers of the vocal fold. In case of cancer or vocal fold paralysis, both involving the deeper layers of the vocal fold, louder voicing significantly enhances the irregularity of vocal fold vibration (jitter). When a tremor component is present in a voice (without known primary neurological disease), it significantly decreases when voicing a little louder. Control of SPL level is thus necessary when comparing, for example, a patient's voice before and after therapy.

Key Words:

• dysphonia, voice acoustics, intensity, loudness, perceptual rating, laryngoscopy, roughness, breathiness