Vocal responses to unanticipated perturbations in voice loudness feedback: An automatic mechanism for stabilizing voice amplitude

Abstract

The present study tested whether subjects respond to unanticipated short perturbations in voice loudness feedback with compensatory responses in voice amplitude. The role of stimulus magnitude (±1,3 vs 6 dB SPL), stimulus direction (up vs down), and the ongoing voice amplitude level (normal vs soft) were compared across compensations. Subjects responded to perturbations in voice loudness feedback with a compensatory change in voice amplitude 76% of the time. Mean latency of amplitude compensation was 157 ms. Mean response magnitudes were smallest for 1-dB stimulus perturbations (0.75 dB) and greatest for 6-dB conditions (0.98 dB). However, expressed as gain, responses for 1-dB perturbations were largest and almost approached 1.0. Response magnitudes were larger for the soft voice amplitude condition compared to the normal voice amplitude condition. A mathematical model of the audio-vocal system captured the main features of the compensations. Previous research has demonstrated that subjects can respond to an unanticipated perturbation in voice pitch feedback with an automatic compensatory response in voice fundamental frequency. Data from the present study suggest that voice loudness feedback can be used in a similar manner to monitor and stabilize voice amplitude around a desired loudness level.

Neural mechanisms underlying auditory feedback control of speech

“…Under feedforward control, task performance is executed from previously learned commands, without reliance on incoming task-related sensory information. Speech production involves both feedforward and feedback control, and auditory feedback has been shown to impact both control processes (Houde and Jordan, 1998;Jones and Munhall, 2005;Bauer et al, 2006;Purcell and Munhall, 2006a).…”

Sensory feedback control of mammalian vocalizations

“…In humans, the reflexive control of speech loudness appears to follow a time course similar to the response to pitch-shifted feedback, or the pitch-shift reflex (PSR) [4,9,49,72,73,136]. Speakers exhibit a reflexive compensatory response to perceived shifts in voice pitch which occurs with a latency of approximately 130 ms and, again, appears not to be under volitional control [4,9,72,73,136].…”

“…This phenomenon, in which a speaker increases or decreases voice amplitude in response to perceived changes in voice loudness feedback, appears similarly reflexive but lends itself to more detailed analyses of the relative effects of amplitude, timing and speech context. For example, Bauer et al found that compensatory changes in voice amplitude exhibited the greatest relative gains in response to the smallest (1dB) perturbations in feedback loudness, and response magnitudes were larger for the soft voice amplitudes than for normal voice amplitudes [4]. Loudness compensation was greater for increases than decreases in feedback loudness, and the mean compensation latency was approximately 150 ms [4,49].…”

“…Speakers exhibit a reflexive compensatory response to perceived shifts in voice pitch which occurs with a latency of approximately 130 ms and, again, appears not to be under volitional control [4,9,72,73,136]. In a related series of experiments [52], when speakers were presented with feedback in which the formant frequency of specific vowels was electronically shifted within a subset of specific words, speakers subsequently made compensatory changes in the production of the pitch-shifted vowels not only in the test words containing the altered vowel, but also in other words containing the same vowel.…”

Loudness perception of vocalization through auditory feedback

“…Voice loudness perturbation paradigms have also been examined to investigate the online control of voice amplitude [4][5][6]. Perturbations were found to result in compensatory responses in voice amplitude with similar latencies as voice pitch feedback perturbations.…”