Mastication noise reduction method for fully implantable hearing aid using piezo-electric sensor

Background: Fully implantable hearing devices (FIHDs) can be affected by generated biomechanical noise such as mastication noise. Objective: To reduce the mastication noise using a piezo-electric sensor, the mastication noise is measured with the piezoelectric sensor, and noise reduction is practiced by the energy difference. Methods: For the experiment on mastication noise, a skull model was designed using artificial skull model and a piezoelectric sensor that can measure the vibration signals better than other sensors. A 1 kHz pure-tone sound through a standard speaker was applied to the model while the lower jawbone of the model was moved in a masticatory fashion. Results: The correlation coefficients and signal-to-noise ratio (SNR) before and after application of the proposed method were compared. It was found that the signal-to-noise ratio and correlation coefficients increased by 4.48 dB and 0.45, respectively. CONCLUSION: The mastication noise is measured by piezo-electric sensor as the mastication noise that occurred during vibration. In addition, the noise was reduced by using the proposed method in conjunction with MATLAB. In order to confirm the performance of the proposed method, the correlation coefficients and signal-to-noise ratio before and after signal processing were calculated. In the future, an implantable microphone for real-time processing will be developed.