The effect of the distance from a laser source on the activation of the acoustic system at three points of stimulation within the ear.

Introduction Optoacustic-induced vibrations can be used to activate the hearing system when induced in various positions within the peripheral hearing organ. In order to investigate this technique for use in the development of new hearing aid technology, this study assesses the efficiency of light-stimulation of the peripheral hearing organ dependent upon the distance between the laser source and the point of stimulation.

Method The auditory threshold of sedated female albino guinea pigs was determined using click-evoked brainstem potentials of 0-80 dB SPL. 10 ns laser pulses at 532 nm wavelength and 10 Hz repetition rate with increasing intensity (0-5; 7; 10; 16; 20; 23 μJ/pulse) were then used to irradiate the tympanic membrane, round window and otic capsule. The laser fiber, with a 365 μm diameter, was positioned at 0; 1; 2.5; 5 and 10mm distance from the three anatomical sites. To assess the neuronal activity, optically induced acoustic brainstem potentials were recorded. The auditory threshold for each distance was identified by the first recorded Jewett complex.

Results The further the distance between the laser and the target, the higher the intensity of the laser pulse required to achieve the auditory threshold. This effect was demonstrated to various levels in all three measurement positions.

Conclusion The optical stimulation using a laser with 532 nm and 10 Hz repetition rate created a progressively weaker signal, the further the distance between source and target. The use of this result in new developments could allow for adjustment of the laser source in order to adapt to the pathology present in each case.

Poster-PDF A-1426.pdf

Gefördert vom European Research Council im Zuge des Siebten Rahmenprogramms der Europäischen Union (RP7/2007-2013) Starting Grant: LaserHearingAids: 311469

Publication History

Article published online:
13 May 2021