title: Cartilage conduction hearing.
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. There is a large gap between the impedances of cartilage and skull bone, such that cartilage vibrations are not easily transmitted through bone. Thus, these methods of conduction are distinct. In this study, force was used to apply a transducer to aural cartilage, and it was found that the sound in the auditory canal was amplified, especially for frequencies below 2 kHz. This effect was most pronounced at an application force of 1 N, which is low enough to ensure comfort in the design of hearing aids. The possibility of using force adjustments to vary amplification may also have applications for cell phone design.
authors.affiliation: Department of Otorhinolaryngology, Head and Neck Surgery, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8522, Japan.
authors.forename: Ryota
authors.initials: R
authors.lastname: Shimokura
authors.affiliation: Department of Otorhinolaryngology, Head and Neck Surgery, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8522, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hosoi
authors.affiliation: Department of Otorhinolaryngology, Head and Neck Surgery, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8522, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Nishimura
authors.affiliation: Department of Otorhinolaryngology, Head and Neck Surgery, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8522, Japan.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Yamanaka
authors.affiliation: Advanced Hearing Concepts Incorporated, 998 Sea Eagle Loop, Bodega Bay, California 94923.
authors.forename: Harry
authors.initials: H
authors.lastname: Levitt
mesh_terms: D000161:Acoustic Stimulation; D000162:Acoustics / Q000295:instrumentation; D000328:Adult; D001301:Audiometry, Pure-Tone; D004425:Ear Cartilage / Q000502:physiology*; D005260:Female; D006309:Hearing; D006801:Humans; D008297:Male; D009038:Motion; D011312:Pressure; D013016:Sound; D013997:Time Factors; D014160:Transducers, Pressure; D014732:Vibration