BME.06 Speaker for the Sensory Impaired Individual

• Sharrafa Khan
• Amir Khansari
• Joseph Mustafa
• Cass Slawik
• Hongtai Zou

“The objective of this project is to design and manufacture a speaker that caters to individuals with sensory impairments. The condition of hearing impairment, which impacts approximately 5% of the populace, commonly presents as a significant reduction in the capacity to perceive sounds with high frequency. The typical auditory range for healthy individuals is between 20 and 20,000 Hz, with a reduction in the upper range to approximately 5,000 Hz for those with hearing impairment. This results in a need for increased volume or a total inability to perceive sounds within that range. The prevailing approach involves the utilization of conventional hearing aids that are inserted into the ear canal to receive signals, subsequently amplifying or compressing the frequency range to render it audible. Although these devices are efficacious in mitigating hearing loss and sensitivity, their users often report dissatisfaction due to issues related to discomfort and fitting. Consequently, there is a risk of discontinuation of use. Therefore, a solution that offers the functionalities of a hearing aid while minimizing the necessity for fitting and prolonged wear periods would be preferable to enhance user satisfaction and improve their quality of life. In order to tackle these concerns, our endeavor involved the development of an external speaker apparatus that offers auditory assistance functionalities, specifically amplification and frequency compression. The proposed solution would enable individuals with hearing impairment to circumvent the fitting challenges associated with conventional hearing aids, while affording them the opportunity to perceive the complete auditory information of a source signal. The device under construction employs a 20V/160W wall adapter to draw mains power. The voltage and current are subsequently reduced by three individual buck converters to supply power to the active components. These components include a linear equalizer for the purpose of attenuating problematic frequencies, a Raspberry Pi 2 Model B v1.1 for digital frequency compression, and a 1752 20W amplifier for amplification. The components are arranged in a series configuration. Subsequently, these electronic apparatuses receive an analog audio input and transmit the signal to a pair of 20W/4Ω speakers. The present device conforms to the established standards for hearing aids in terms of amplification and presents a rational plan for linear frequency compression. The device exhibits a maximum sound pressure level (SPL) of approximately 93 dB SPL, while maintaining an amplification level that does not surpass 30 dB above the original signal. The aforementioned apparatus implements linear frequency compression through the process of compressing a spectrum of frequencies, typically spanning from 20 to 20,000 Hz. This compression is achieved by applying a linear factor that reduces frequencies above the lower limit. The linear factor is determined by multiplying a given frequency by a value ranging between 0 and 1. This yields a compression ratio of roughly 0.5 through adequate frequency compression.
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