The role of threat appraisal in modulating vocal response to aversive internal stimuli

Background: Threat appraisal has been suggested to play a role in the development and maintenance of maladaptive vocal behaviors leading to chronic vocal hyperfunction. Specifically, a speaker’s interpretation of internal or external stimuli is thought to influence neural control of voice production, contributing to a faulty motor pattern that is maintained through neuroplasticity in the context of possible sensorimotor deficits. However, research in this area has so far focused on external threats, such as public speaking, and the role of sensory threats affecting the airway remains unclear.

Objective: The objective of this study was to investigate the role of threat appraisal in modulating the vocal response to aversive airway sensations, using a respiratory discomfort paradigm.

Methods/Design: Fifty-eight healthy females aged 18-44 years old underwent an experimental paradigm during which they were exposed to different levels of respiratory discomfort through repeated breath holds of various durations. Immediately after each breath hold, participants were instructed to produce a sustained /a/. Sensory appraisal (respiratory discomfort), threat appraisal (fear of suffocation), and vocal response (perceived vocal effort and acoustic measures of voice quality) were recorded after each trial. Acoustic measures consisted of smoothed cepstral peak prominence (CPPS) and harmonics-to-noise ratio (HNR). Regression models accounting for repeated measures were generated to assess the role of threat appraisal in modulating the relationship between airway sensation and vocal response.

Results: A significant interaction between respiratory discomfort and fear of suffocation was found to predict both perceived vocal effort (p=0.0009) and CPPS (p=0.0403). In fact, speakers with higher fear of suffocation showed a steeper rise in perceived vocal effort and a greater reduction in vocal quality as respiratory discomfort increased when compared to speakers with lower fear of suffocation. The interaction remained significant even when controlling for age, trait and state anxiety, and oxygen saturation during breath holds.

Conclusions: In this study, the effect of aversive airway sensations on the voice was modulated by the speaker’s threat appraisal, suggesting a defensive response. This finding has implications for the treatment of patients with maladaptive vocal behaviors that are elicited and perpetuated by aversive sensory triggers affecting the airway.