Altered Auditory Feedback via Bone Conduction: Evaluating the Forbrain Device and Sidetone Amplification

Purpose This study assesses changes in speech production caused by altered auditory feedback provided through two bone conduction devices. The first device uses sidetone amplification through bone conduction head- phones and the second device, called Forbrain®, applies a two-band equalizer filter to the voice signal and pro- vides this altered auditory signal through bone conduction headphones. Together with objective voice acoustics, self- reported vocal fatigue ratings were also assessed. Methods Speech samples were recorded during a vocal loading task in which speakers received different types of altered auditory feedback delivered from the two devices, and a condition with no feedback. At consistent intervals during each condition, the participants provided vocal fatigue ratings. The voice recordings were processed to calculate acoustic parameters. The effects of the feedback conditions on the vocal fatigue ratings and acoustic voice parameters were analyzed. Results The altered auditory feedback conditions resulted in reduced magnitudes of vocal fatigue and significant variations in acoustic voice parameters compared to the condition with no feedback. Conclusions This study provides evidence that altered auditory feedback delivered by bone conduction devices can reduce vocal fatigue in users.