Underwater Hearing and Sound Localization with and without an Air Interface

Abstract

The presence of air around the pinna and inside the external ear canal did not improve underwater hearing sensitivity or sound localization. These results support the argument that bone conduction plays the main role in underwater hearing.

Experiments on the mechanism of underwater hearing

“…Actually we do not agree, our results clearly argue for the sound transmission via the middle ear. Neoprene hoods worsen underwater sound perception, which is known from the literature [7,10] and could be supported by our findings. However, we could not support the measurements reported by Hollien and Feinstein [5], according to which it makes no difference whether there is a perforation in the neoprene hood above the ear or not: our recordings showed at least a small effect.…”

“…This in agreement with the findings of Bauer and co-workers [1,3] and in contradiction to the assumption by Hollien et al [4,5]. Other authors favor a third theory, according to which as a dual path theory both mechanismsbone conduction and middle ear conductionplay a role, contributing differently to underwater sound perception depending on different frequencies [7,8]. One of the main difficulties in underwater hearing is that the acoustic impedance of water is much higher than that of air.…”

“…However, sound perception did not significantly improve when a tube was inserted, penetrating the neoprene hood and allowing a direct contact between the outer ear canal and the ambient water. From these experiments, Hollien et al concluded that underwater hearing was related to bone conduction, an assumption still present in recent publications [7].…”

“…The other factor is that sound localization is much more difficult under water than in air. However, most authors agree that indeed some directional hearing is possible under water, although not comparable to that in air [1][2][3][4][5][6][7][8][9]. Hollien and Feinstein [5], favoring the bone conduction theory, argued that the mechanical coupling from earphone to the skull is much more direct in water than in air.…”

Underwater Acoustic Source Localisation Among Blind and Sighted Scuba Divers: Comparative study

“…22 Recently, Shupak et al tested the use of masks with an air pocket around the ears as a method of improving underwater auditory perception; however, the authors concluded that the masks did not significantly improve underwater hearing. 23 Among scuba divers, poor sound localisation is a source of concern as certain sounds may indicate imminent danger, such as an approaching motorboat. In the current study, the results of the spatial localisation tasks among the sighted controls indicated that they could only immediately identify the source of sound at a rate of 24%; therefore, the task was feasible in only one out of four attempts.…”