Development of cartilage conduction receiver available in noisy condition

Abstract

Sound information is known to travel to the cochlea via either air or bone conduction. However, a vibration signal, delivered to the aural cartilage via a transducer, can also produce a clearly audible sound. This type of conduction has been termed “cartilage conduction.” The aural cartilage forms the outer ear and is distributed around the exterior half of the external auditory canal. In cartilage conduction, the cartilage and transducer play the roles of a diaphragm and voice coil of a loudspeaker, respectively. A benefit of using the cartilage conduction is to be able to amplify the sound in the canal by pushing the transducer on the cartilage more strongly. And when the pushed ear tragus obscures the canal, the sound pressure in the canal reaches a maximum and the environmental noise is blocked at the same time. In our study, participants could catch a speech clearly in this way in different kinds of noise condition (speech noise, road noise, station noise, and cleaner noise in 50, 60, 70, and 80 dB). This benefit can be applied for a smartphone for workers who have to answer the phone no matter what noisy condition they are in.