Laser interferometric measurement of the micromechanics of the inner ear

Anthony W. Gummer; Werner Hemmert; Hans-Peter Zenner

doi:10.1117/12.200866

1 February 1995 Laser interferometric measurement of the micromechanics of the inner ear

Anthony W. Gummer, Werner Hemmert, Hans-Peter Zenner

Proceedings Volume 2329, Optical and Imaging Techniques in Biomedicine; (1995) https://doi.org/10.1117/12.200866
Event: International Symposium on Biomedical Optics Europe '94, 1994, Lille, France

Abstract

Recent advances in optical techniques for vibration measurement have made it feasible to purchase commercially available laser Doppler velocimeters that, in combination with a light microscope, are capable of detecting velocities of poorly reflecting biological materials down to fractions of a micrometers s^-1. Thus, in our particular application, the aim is to understand the micromechanics of the inner ear, particularly in the nanometer region where the ear is first able to detect sound. With currently available devices, it is now possible to make the necessary vibration measurements without need of introducing reflecting materials onto the object of interest. This not only avoids inertial loading, but also allows focusing through cellular layers onto otherwise inaccessible structures. Here we present the results of micromechanical experiments for the in vitro inner ear of the guinea pig, the most commonly used model in auditory physiology. Our experiments concentrate on the third and fourth cochlear turns because in this region the different cellular structures of the organ of Corti are optically accessible with present technology. The mechanical responses of all examined structures, including the basilar membrane, were equally frequency selective, but linear below 90 dB SPL, suggesting that active mechanical tuning is not as pronounced in the apex as in the base of the cochlea. This has important consequences for signal processing in the inner ear.

Citation Download Citation

Anthony W. Gummer, Werner Hemmert, and Hans-Peter Zenner "Laser interferometric measurement of the micromechanics of the inner ear", Proc. SPIE 2329, Optical and Imaging Techniques in Biomedicine, (1 February 1995); https://doi.org/10.1117/12.200866

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