• Open Access

Is cartilage conduction classified into air or bone conduction?

Authors


  • This research was supported by a Health and Labour Science Research Grant for the Sensory and Communicative Disorders from the Ministry of Health, Labour and Welfare, Japan. This study was also supported by JSPS KAKENHI Grant Number 23791924 and Adaptable and Seamless Technology Transfer Program through target-driven R&D, JST Grant Number AS251Z00168P. The authors have no other funding, financial relationships, or conflicts of interest to disclose.

Abstract

Objectives/Hypothesis

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.

Study Design

Experimental study.

Method

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.

Level of Evidence

N/A. Laryngoscope, 124:1214–1219, 2014

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