Sound reaches the auditory system through air conduction (AC) via the ear canal or bone conduction (BC) via vibrations of the temporal bone, and both pathways are often activated simultaneously in real environments such as trains and vehicles; environmental sounds are transmitted via AC, while mechanical vibrations may be perceived not only as tactile stimuli but also as BC-like vibrational stimuli. Previous studies have demonstrated AC–BC interference for identical pure tones, but directly measuring cochlear vibrations during simultaneous acoustic and vibrational stimulation remains challenging. Computational simulation can therefore help clarify intracochlear mechanics under such combined stimulation. However, intracochlear mechanical responses under simultaneous AC and vibrational stimulation at different frequencies, which more closely reflect real-world environments, remain insufficiently characterized. In this study, cochlear vibrations under simultaneous AC and vibrational stimulation were simulated using a computational model of human cochlea. Displacement-driven BC stimulation consistently generated basilar-membrane (BM) traveling waves comparable in overall pattern to those induced by AC stimulation. Under same-frequency stimulation, the BM response at the AC-defined CF location varied systematically with AC–BC relative phase and relative magnitude, including marked reductions consistent with destructive interference. Under different-frequency stimulation, the traveling-wave envelope departed from a single spindle-shaped profile and could become bimodal or otherwise non-spindle-shaped, indicating superposition of concurrent response components. These results show that AC–BC interference depends on stimulus magnitude, phase, and frequency, and provide a basis for quantitatively assessing vibroacoustic interactions in the cochlea.
Lee et al. (Thu,) studied this question.