Combining auditory and tactile inputs to create a sense of auditory space

To localize a sound, the auditory system uses multiple cues, including binaural differences in timing and level that arise from the separation of the ears by the solid mass of the head. It has repeatedly been shown that the ability to utilize these cues is plastic and experience-based. Vibrotactile input shares many common features with auditory signals, and there is some overlap between the frequency range of the sensitivity of the ear and skin. In this study, we examine whether the auditory system is capable of combining auditory and tactile inputs to localize sounds using a multi-speaker array. To induce deficits in azimuthal localization, one ear was plugged. To examine cross-modal localization, the input level to the plugged ear was recorded via microphone, and a vibratory signal that was perceptually equal in intensity was presented to the shoulder on the same side as the plugged ear. The participant's ability to localize low-pass, band-pass, high-pass, and broadband sounds was measured. Results showed that relative to baseline (plugged) conditions, localization performance improved, suggesting that listeners can combine auditory and tactile information to create a sense of auditory space.