THE DESIGN AND CONSTRUCTION OF THE HEARING AID DEVICE
ABSTRACT
Hearing aid device is a small electronic gadget that is fit in or behind the ear to improve one’s hearing and consequently communication ability.This research work involves the design and development of a hearing aid device withpre-amplifier; an acoustic signal picked-up using a condenser microphone. TDA 2822M IC is configured to produce an audio amplification which is converted to audio signal through a headphone. Designed equations were employed to calculate the physical parameters of the circuit. After the design, the circuit was constructed and tested on 4 people with partial hearing problem. The result showed that there was a significant improvement in the hearing ability of all the patients tested. The final test showed that the device could prove very useful for people with partial hearing problems. However, the device had no impact on persons suffering from complete deafness. For further improvement, it is recommended that a wireless hearing aid device should be designed and constructed to reduce the weight. The casing of the hearing aid should be made up of more portable, qualitative and lighter plastic material so as to reduce the overall weight and size. During the design, more care should be taken so as to avoid feedback signal between the microphone and the headphone which may result in noisy signal.
CHAPTER ONE
INTRODUCTION
1.1 BACKGROUND TO THE STUDY
Hearing is one of the five senses along with vision, taste, smell and touch. The ear serves asa receiver of incoming sounds. Although the ear receives sound and is the sense organ for hearing, it is the brain and central nervous system that interpret the sound. The human auditory system can generally hear sounds within the frequency range of 20 Hz and 20 kHz but the frequency range between 100Hz and 6 kHz contains most of the information of human voice (Kinsler, Frey, Coppers, and Sanders, 1982). Although the sensation of hearing requires an intact and functioning auditory portion of the central nervous system as well as working ear, human deafness (extreme insensitivity to sound) and hearing loss most commonly occur because of damages of the ear, rather than the central auditory system.
Hearing aid device is a small electronic gadget that is fit in or behind the ear to improve one’s hearing and consequently communication ability (Yusuf, 2015). While some people are born with hearing problem some others develop it as they grow. This problem can occur as a result of disease, aging, and injury from noise or intake of certain medicines (N.I.D.C.D, 2010). Hearing problems could be that of complete deafness or partially impaired type. Hearing problem could occur after a person learned to talk (post lingual) or those with trilingual deafness that is, deafness that occurs before a person learns to talk. Deafness, whatever the degree or course, is generally a source of worry and frustration to the patient concerned as it affects almost all aspects of one’s life.
