Abstract
.Significance: Optoacoustic-induced vibrations of the hearing organ can potentially be used for a hearing device. To increase the efficiency of such a hearing device, the conversion of the light energy into vibration energy within each type of irradiated tissue has to be optimized.Aim: To analyze the wavelength-dependency of optoacoustic-induced vibrations within the tympanic membrane (TM), and to define the most efficient and best-suited optical stimulation parameters for a novel auditory prosthesis.Approach: Single nanosecond laser pulses, continuously tunable in a range of visible to near-infrared, were used to excite the guinea pig TM. The induced vibrations of the hearing organ were recorded at the malleus using a laser Doppler vibrometer.Results: Our results indicate a strong wavelength-dependency of the vibration’s amplitude correlating with the superposition of the absorption spectra of the different specific tissue components.Conclusions: We investigated the spectrum of the vibrations of the hearing organ that were induced optoacoustically within a biological membrane embedded in air, in an animal model. First applications for these results can be envisioned for the optical stimulation of the peripheral hearing organ as well as for research purposes.
Highlights
The optoacoustic effect is widely used in medicine and industry for photoacoustic spectroscopy and photoacoustic imaging, e.g., tomography or microscopy.[1,2]
A detailed optoacoustic stimulation strategy to vibrate the hearing organ using a custom-designed laser pulse amplitude modulation is described by Stahn et al.[6]
The vibration velocity measured at the head of the malleus while optoacoustically stimulating the tympanic membrane (TM) at different wavelengths (420 to 2200 nm) demonstrated the highest vibration amplitude at the beginning of each recording
Summary
The optoacoustic effect is widely used in medicine and industry for photoacoustic spectroscopy and photoacoustic imaging, e.g., tomography or microscopy.[1,2] This effect is the result of the absorption of pulsed light in an absorber medium inducing a thermal expansion and contraction of the substrate. Through these periodic variations of the tissue density, a sound source is created. Previous reports demonstrate that this effect could potentially be used to stimulate the hearing organ to compensate for deficits in patients who are not sufficiently supplied with currently available hearing aids.[3,4,5] A detailed optoacoustic stimulation strategy to vibrate the hearing organ using a custom-designed laser pulse amplitude modulation is described by Stahn et al.[6]
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