IEC 60118: Hearing Aids — Where Electroacoustics Meets Audiology

Hearing Aid Standards: How IEC 60118 Ensures Clear Sound for Hundreds of Millions

IEC 60118-12:1996 specifies hearing aid electroacoustic measurement methods. A hearing aid is not a simple amplifier — it must extract speech from noise, compensate for the user hearing loss profile, and avoid acoustic feedback (whistling — the most frustrating problem for users).

Key metrics: (1) OSPL90 — output SPL at 90 dB input, must be limited below the patient discomfort threshold (typically ≤130 dB SPL). (2) Frequency response — must provide frequency-selective gain, with maximum amplification in the bands where the patient hearing loss is greatest (typically high frequencies 2–8 kHz). (3) Equivalent input noise — the self-noise of the hearing aid must be inaudible in quiet environments (typically below 25 dB SPL).

TN Lab — Hearing aids are precision devices integrating electroacoustics, signal processing, and audiology.