Effects of hardness and dimension of pinna and auricular hematoma on detection threshold of cartilage conduction*

In cartilage conduction (CC), a vibrator is presented onto the cartilage of the ear instead of the bony parts of the head used in ordinary bone conduction (BC). Because the auricle cartilage is softer and lighter than the bone, it doesn't require as much pressure as BC, which may cause discomfort (or pain) in the area where a BC transducer is being pressed. However, CC is a relatively new technology, and whether the less dense characteristics of cartilage, which varies from person to person, result in a better sound perception is still being studied. In this paper, we focused on investigating how the hardness and size of the auricle or pinna affect the effectiveness of CC. We used pure-tone hearing thresholds to evaluate this objectively. We also measured the thresholds of CC in subjects with auricular hematoma or "cauliflower ear" (misshapen ears commonly caused by close contact sports) to see if it affected CC differently. Our results indicate that the hardness and size of the auricle affect CC thresholds and that subjects with auricular hematoma have different perceptual characteristics compared to the normal ear group. These differences are believed to be caused by changes in hardness and mass.