Development of monaural and binaural behind-the-ear cartilage conduction hearing aids

Hosoi (2004) found a pathway for clear sound transmission via aural cartilage. Our research group is developing a new hearing aid using this mechanism. The cartilage conduction hearing aid can be used in patients who cannot insert the earplugs of conventional hearing aids. The cartilage conduction hearing aid (model HD-GX) is composed of a main unit, a transducer, and a fitting part. The ring-shaped fitting part is placed in the entrance of the ear canal, and the vibration at the cartilage then generates sound in the external auditory canal. The cartilage conduction sound remains in the canal and reduces the risk of acoustical feedback. Considering this advantage, we designed it to wear behind the ear (BTE) (model HD-GX2). As binaural cartilage conduction can present sound directivity equivalent to that of air conduction, we then developed a binaural cartilage conduction hearing aid (model HD-GX3) by combining two BTE hearing aids.