title: Is cartilage conduction classified into air or bone conduction?
abstract: OBJECTIVE
  The aim of this study was to establish the sound transmission characteristics of cartilage conduction proposed by Hosoi (2004), which is available by a vibration signal delivered to the aural cartilage from a transducer.
  
  
  METHODS
  Experimental study.
  
  
  METHODS
  Eight volunteers with normal hearing participated. Thresholds at frequencies of 0.5, 1, 2, and 4 kHz for air conduction, bone, and cartilage conductions were measured with and without an earplug. The sound pressure levels on the eardrum at the threshold estimated with a Head and Torso Simulator were compared between air and cartilage conductions. The force levels calibrated with an artificial mastoid at the threshold were compared between bone and cartilage conductions.
  
  
  RESULTS
  The difference in the estimated sound pressure levels on the eardrum at the thresholds between air and cartilage conductions were within 10 dB. In contrast, the force levels at the thresholds for cartilage conduction were remarkably lower than those for bone conduction. These findings suggested that sounds were probably transmitted via the eardrum for cartilage conduction. The threshold shifts by an earplug showed no significant difference between bone and cartilage conductions at 0.5 kHz. At 1 and 2 kHz, the threshold-shifts increased significantly in the order of bone, cartilage, and air conductions. These results suggested that airborne sound induced by the vibration of the cartilaginous portion of the ear canal played a significant role in sound transmission for cartilage conduction.
  
  
  CONCLUSIONS
  Cartilage conduction has different characteristics from conventional air and bone conductions.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Nara Medical University, Kashihara, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Nishimura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hosoi
authors.forename: Osamu
authors.initials: O
authors.lastname: Saito
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Miyamae
authors.forename: Ryota
authors.initials: R
authors.lastname: Shimokura
authors.forename: Toshie
authors.initials: T
authors.lastname: Matsui
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Yamanaka
authors.forename: Harry
authors.initials: H
authors.lastname: Levitt
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D000388:Air; D001309:Auditory Threshold / Q000502:physiology*; D001844:Bone Conduction / Q000502:physiology*; D004424:Ear Canal / Q000502:physiology*; D004425:Ear Cartilage / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D014732:Vibration
keywords: Occlusion effect; airborne sound; aural atresia; aural cartilage; bone anchored hearing aid