Listener Perception of Voice Tremor Induced by Forced Oscillation of the Respiratory System
The purpose of this investigation was to determine the relation between respiratory tremor and the perception of the resultant voice tremor. Forced oscillation of the respiratory system was employed to simulate variations in alveolar pressure such as are characteristic of voice tremor of respiratory origin. Five older, healthy male speakers produced vowel and sentence utterances using their habitual pitch, loudness, rate, and quality while forced sinusoidal pressure changes were applied directly to the external surface of their respiratory system. Speakers were also directed to repeat each vowel and sentence utterance while modifying pitch, loudness, and quality. A panel of clinicians completed the perceptual tasks. They were first asked to detect threshold of voice tremor and then using pair comparisons, determine which sample had the greater magnitude. Results indicate that the detection threshold for tremor of respiratory origin was different for vowels and sentences. In addition, the magnitude of tremor was judged to be greater when utterances were produced either at higher pitch levels, ½ habitual loudness levels, or using a breathy voice quality.