Altered Auditory Feedback via Bone Conduction Reduces Vocal Fatigue

Objective: Emerging evidence indicates that impaired integration between auditory feedback and voice production underlies voice disorders. Altered auditory feedback (AAF) devices aim to target this impairment. For AAF, bone conduction devices may be a more ecologically valid option compared to over-the-ear headphones, as there is no occlusion of the ears. This allows speakers to hear both their communication partner(s) and the real time auditory feedback for their voice, simultaneously. Bone conduction AAF devices could be especially useful for occupational voice users, such as teachers. The goal of the present study was to compare the effects of two bone conduction devices that provide altered auditory feedback.

Methods: Twenty vocally healthy participants (19 − 33 years; mean (SD) 25.5 (3.85) years) participated in a vocal loading task in which they read aloud with a raised vocal effort level while using a standard Forbrain® device (filtered AAF via bone conduction), a modified Forbrain® device (sidetone amplification AAF via bone conduction), and a control condition (no AAF). The participants rated their vocal fatigue on a 100 mm visual analog scale every two-minutes during the vocal loading task. Additionally, pre- and post- vocal loading task voice samples were recorded and analyzed for acoustic voice parameters.

Results: Across all participants, the use of the Forbrain® resulted in vocal fatigue ratings that were 9 mm lower (p < 0.05) when compared to the condition with no feedback. Sidetone amplification resulted in vocal fatigue ratings that were 15 mm lower (p < 0.05) when compared to the condition with no feedback. During the pre- and post- voice samples, sound pressure level decreased significantly during feedback conditions (p < 0.05), and spectral measures (mean, standard deviation, and skewness of the long-term average spectrum) significantly changed during feedback conditions (p < 0.05).

Conclusions: The results promote bone conduction altered auditory feedback devices as possible preventative tools to reduce self-reported vocal fatigue and compensatory voice production in vocally healthy individuals.