Effects of size and hardness of pinna on cartilage conduction hearing: Comparison between auricular hematoma and normal subjects

Bone conduction (BC) is a method of perceiving sound via biological tissue by presenting a vibrator to the skull. BC has been applied to hearing aids for the conductive hearing loss and earphones which can be used even in noisy environments. However, a vibrator needs to be pressed strongly in BC and this causes discomfort and pain. Therefore, cartilage conduction (CC), in which a vibrator is presented onto the auricle cartilage instead of the skull, has been proposed to solve these problems and actually applied to smartphones and hearing aids. However, influence of the properties of the auricle itself on CC is still being studied. In this paper, we measured the auricle hardness, size, and thresholds of CC in patients with auricular hematoma and normal ear-shape subjects. We compared results with between these two subjects' groups and investigated relationships between hardness and size of the auricle and thresholds of CC. Our results indicate that subjects with auricular hematoma have different perceptual characteristics compared to the normal-ear group and that the auricle hardness and size affect thresholds of the cartilage conduction.