Auditory distance estimation of virtual sound sources with bilateral bone conduction stimulation

Auditory distance perception relies on multiple acoustic cues, with sound level serving as the dominant cue. While near-field distance perception under air conduction (AC) stimulation has been extensively studied, comparatively little knowledge is known about distance perception under bilateral bone conduction (BC) stimulation. The present study investigated near-field auditory distance perception under AC and BC stimulation using virtual sound sources presented at distances between 0.2 and 1.0 m and at azimuths of 45°, 90°, and 135°. Two experiments were conducted, one with natural distance-dependent level cues preserved and one with level cues removed via normalization. Distance estimates were quantified using power-function exponents as a measure of perceptual distance compression. When level cues were preserved, distance perception did not differ significantly between AC and BC stimulation. Under level-normalized conditions, perceived distance ranges were significantly reduced for BC compared with AC at lateral azimuths. These results are consistent with the interpretation that sound level is the primary cue for auditory distance perception under both stimulation modalities, and that binaural cue degradation under BC stimulation limits distance accuracy when level cues are unavailable. The findings have implications for the design and signal processing of BC auditory devices intended to support spatial hearing.