Electronic Design of an Analog Equalizer for a Bone Conduction Stethoscope

Abstract

Abstract The necessity and interest of audiologists to finely tune and customize sound frequencies according to individual patient needs, has inspired us to develop and integrate an equalizer to a bone conduction stethoscope. The project designs an analog amplifier equalizer circuit that is used for volume control and frequency selection. It captures sounds from the skull bone with the help of a skin microphone hoping to provide audiologists a flexible tool that can isolate specific frequency bands for analysis, auditory experience diagnosis and troubleshooting of bone conduction hearing aids. The switching options designed on the equalizer has bandpass filters for the audiometric frequencies with the possibility to focus the listening range to both low and high frequencies and thereby encourage audiologists to select the desired ranges of inspection. The project plan was designed to use the electronic features to categorize audio spectrum into bass (125 Hz to 1 kHz), wide (125 Hz to 8 kHz) and treble (1-8 kHz) for testing. The test is done on two subjects with the use of a skin microphone having a strategy to check one’s own voice to understand the perception of booming effect, crispness and clarity along with normal speech auditory range of bone conduction voice. The test subjects also experimented by hearing each other’s voice through the equalizer to understand the audio spectrum as mimicked in normal hearing conditions as a reference. The results showed that the auditory experience was in sync with the theoretical expectations. To conclude, the design and testing of the prototype showed that it is a promising tool for audiologists in near future.