# Soft Tissue Conduction Activates the Auditory Pathway in the Brain

## TL;DR

This study shows that soft tissue vibrations can activate the brain's auditory pathways, not just touch receptors, offering a new way to hear.

## Contribution

The study confirms that soft tissue conduction stimulates the auditory nerve and brainstem, not just tactile pathways.

## Key findings

- Participants could recognize speech delivered via soft tissue conduction.
- Pure tone audiograms showed responses to soft tissue vibrations.
- Ear plugs minimized air-conducted sound interference, confirming soft tissue pathway activation.

## Abstract

Soft tissue conduction is a mode of hearing which differs from air and bone conduction since the soft tissues of the body convey the audio-frequency vibrations to the ear. It is elicited by inducing soft tissue vibrations with an external vibrator applied to sites on the body or by intrinsic vibrations resulting from vocalization or the heartbeat. However, the same external vibrator applied to the skin sites also excites cutaneous mechanoreceptors, and attempts have been made to assist patients with hearing loss by audio–tactile substitution. The present study was conducted to assess the contribution of the auditory nerve and brainstem pathways to soft tissue conduction hearing. The study involved 20 normal hearing students, equipped with ear plugs to reduce the possibility of their response to air-conducted sounds produced by the external vibrator. Pure tone audiograms and speech reception (recognition) thresholds were determined in response to the delivery of the stimuli by a clinical bone vibrator applied to the cheek, neck and shoulder. Pure tone and speech recognition thresholds were obtained; the participants were able to repeat the words they heard by soft tissue conduction, confirming that the auditory pathways in the brain had been stimulated, with minimal involvement of the somatosensory pathways.