ISSN: 2250-3005 - ijcer

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International Journal Of Computational Engineering Research (ijceronline.com) Vol. 2 Issue. 8Exploring a Microcontroller Based Hearing Aid with an Output LevelIndicator1 Aru Okereke Eze , Eng. Dr. Gozie Ihekweaba and 3 Ngwu Rosemary ChinyereDepartment of Computer EngineeringMichael Okpara University of Agriculture, Umudike, Umuahia, Abia State, NigeriaAbstract:This research explores the design and implementation of a microcontroller based electronic Hearing aid with outputlevel indicator. The incoming sound oscillates the base of a transistor which in turn amplifies the signal at the collect or. Theoutput is interfaced to an ADC which converts the signal to digital output. After the conversion, the microcontrollerprocesses the signal and further feeds it in to the DAC for an analog conversion. This output is now fed into the audio levelindicator, LM3915, to indicate the level of the audio signal at the ear phone.Keywords: Microcontroller, Hearing Aid, Digital, Ear, Noise, Electronics.1. IntroductionDigital hearing aids can do wonders for faded hearing. With the technological advancement in the society, hearingaids can significantly enhance the quality of life for most people with hearing impairment. Therefore, the electronic hearingaid is designed to make sounds louder and therefore easier to hear. Also the design of the circuitry keeps the sound frombecoming too loud and helps reduce the effects of background noise.The two basic types of technology for hearing aids are analog and digital. The first to exist, analog hearing aidsprocess electrical sound in the analog domain; the more recent digital hearing aids process electrical sound in the digitaldomain. The earliest analog hearing aids simply amplified both speech and noise, and were ordered after testing todetermine the particular frequency response needed by the patient. Newer analog hearing aids can be programmed duringthe fitting process, and some have multiple listening profiles that the patient can select with a button on the hearing aid.[ 1].Manufacturers are moving toward their third or fourth generation of digital products. Digital technology is more stable overtime. There are fewer components to go wrong and fewer components that are susceptible to moisture and aging changes.This means that the sound you experience on the first day you receive the hearing aid stays cons istent until the program ischanged.[2] In recent years, there has been an increasing trend toward fitting BTE( Behind The Ear) hearing aids,including receiver-in-canal (RIC) instruments. It is estimated that 51% of the hearing aids fitted in the U.S. are BTEinstruments, rather than custom products [3]. In a survey by Kochkin of 2500 hearing aid users, patients reported a desire forhearing aids that do not feedback (85%), fit comfortably (79%), and are less visible (52%) [4]. In this work, we will explorea digital hearing aid with Output level indicator (LM3915) using the microcontroller Atmel 89c52, analog and digitalconverters.We preset in section 2 system design, section 3 principle of operation, section 4 user guide, section 5 Conclusion.2. System DesignThe system is designed in such a way that the output is an analog signal which needs to be converted into digitalsignal for onward interface to a microcontroller. In this work, the ADC was handy to settle the conversion problem. Itconverts the analog signal to digital signal. After the conversion processes, the microcontroller gives out a digital outputwhich requires conversion back to its analog state. Hence, the output signal can be connected to a microphone to ascertainthe nature of the signal.This analog output is then fed into lm3915, an audio level indicator, to process and give a required graphic result ofthe signal strength. Apart from analog and digital conversions, the emphasis is also on the individual components of thedevices employed and their relevance to the design.Some of the materials used in this work are listed below:Audio level indicator (LM3915)Analog-to-digital converter (ADC0804)Digital-to-analog converter (DAC0808)Microcontroller (Atmel 89c52)Resistors||Issn 2250-3005(online)|| ||December||2012|| Page 253
International Journal Of Computational Engineering Research (ijceronline.com) Vol. 2 Issue. 8CapacitorsTransistorsLight Emitting Diodes (LED)Ear PhonesFigure 1: Block Diagram of Hearing AidMicrophoneEarphoneBroadbandAmplifierAudioAmplifierCircuit to beDesigned:Custom FilteringCircuit to UndoHearing LossesFigure 2. Functional Diagram of Hearing Aid.FIG 3. CIRCUIT DIAGRAM OF THE DESIGN||Issn 2250-3005(online)|| ||December||2012|| Page 254
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ISSN: 2250-3005 - ijcer

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