Fabrication and Performance Evaluation of a Low-Cost Hearing Aid Amplifier Using Locally Sourced Components for Age-Related Hearing Loss
Keywords:
Age-related hearing loss, LM386, TL072, bandpadd filter, Bayelsa State, Nigeria, low-cost hearing aid, ASPEN Plus, presbycusis, total harmonic distortion, tonal languageAbstract
Background: Age-related hearing loss (presbycusis) affects approximately two-thirds of adults aged 70 years and older globally, with disproportionate impact in low-resource settings. In Nigeria, where over 200 million people include significant elderly populations in states such as Bayelsa, the cost of digital hearing aids (exceeding NGN 300,000) places them beyond reach for most affected individuals. Furthermore, tonal languages spoken in Nigeria rely heavily on pitch discrimination for semantic comprehension.This study designed, fabricated, and evaluated a low-cost hearing aid amplifier using locally sourced electronic components, specifically adapted for tonal language comprehension and battery-operated for off-grid use in Bayelsa State, Nigeria. The amplifier circuit was designed around the LM386 low-voltage audio power amplifier IC and the TL072 dual JFET-input operational amplifier for preamplification. A fourth-order active bandpass filter (300-3400 Hz) was implemented. ASPEN Plus process simulation software was employed to optimize circuit parameters including THD, power consumption, and frequency response. Performance evaluation included THD measurement, SPL calibration, frequency response analysis, and user acceptability testing with 30 elderly subjects (60-80 years) in Yenagoa, Bayelsa State. The prototype achieved a voltage gain of 20-200 (26-46 dB), THD of 0.22% at 1 kHz (gain=50), and maximum output power of 325 mW at 9V supply. The bandpass filter exhibited -3 dB cutoffs at 298 Hz and 3410 Hz. User testing showed 87% average satisfaction, with tonal language comprehension scores of 78% (Yoruba), 75% (Igbo), and 80% (Ijaw) in the 60-65 age group. The total component cost was NGN 1,250, representing 96% cost reduction. The fabricated low-cost hearing aid amplifier demonstrates adequate electroacoustic performance for age-related hearing loss compensation, with specific advantages for tonal language users in resource-constrained Nigerian settings.
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