IEC 60118-8:2005

Overview

IEC 60118-8:2005 is an international standard developed by the International Electrotechnical Commission (IEC) that defines methods for measuring the performance characteristics of hearing aids under simulated in situ working conditions. Specifically, this standard outlines procedures to replicate the acoustical effects experienced by a median adult wearer, enabling accurate evaluation of hearing aid functionality in a laboratory environment.

The standard provides detailed guidelines for conducting simulated in situ measurements, including a simplified method for insertion gain measurement and procedures for determining the directivity index (DI) of directional microphones in hearing aids, focusing on the horizontal plane. This edition also specifies tolerances for measurement results to ensure consistency and reliability across testing laboratories.

Key Topics

• Simulated In Situ Testing: Techniques to replicate realistic acoustic conditions of hearing aid wearers, enabling objective performance measurement.
• Test Equipment Requirements: Specifications for the acoustic test environment, including sound sources, manikins representing the human ear, ear simulators, and measurement devices.
• Measurement Procedures: Step-by-step processes to measure key hearing aid performance parameters, including:
  • Simulated insertion gain using both constant reference input sound pressure levels and constant ear simulator SPL methods.
  • Directional characteristics and directivity index (DI) of directional microphones.
  • Output sound pressure level for loud input signals (OSPL90).
• Measurement Uncertainty and Tolerance: Defined maximum expanded uncertainty (Umax) values to validate and ensure measurement reliability.
• Graphical Recording: Templates and charts recommended for documenting frequency response and gain curves during testing.

Applications

IEC 60118-8:2005 is essential for hearing aid manufacturers, testing laboratories, and research institutions involved in:

• Quality Assurance and Compliance Testing: Ensuring hearing aids meet international performance standards before market release.
• Product Development: Assessing the acoustic behavior of prototype hearing aids under controlled yet realistic conditions.
• Regulatory Approval Processes: Providing standardized test data for medical device certification and regulatory body submission.
• Performance Benchmarking: Comparing directional microphone capabilities and gain characteristics across different hearing aid models.
• Audiological Research: Facilitating studies on how hearing aids perform in real-world acoustic environments by using manikin-based simulation.

This standard supports the delivery of reliable, reproducible results critical for optimizing hearing aid design and enhancing user satisfaction.

Related Standards

Users of IEC 60118-8:2005 may also consider referencing these complementary standards for a broader scope of hearing aid testing and electroacoustic measurements:

• IEC 60118-0 – Electroacoustics – Hearing aids – Part 0: Measurement of hearing aid performance characteristics.
• IEC 60118-7 – Electroacoustics – Hearing aids – Part 7: Measurement of the frequency response of hearing aids.
• IEC 60318 Series – Electroacoustics – Ear simulators for the measurement of hearing aids.
• ISO 8253 – Acoustics – Audiometric test methods addressing hearing assessment procedures.

Together, these standards define a comprehensive framework for evaluating hearing aid acoustic performance, supporting innovation and ensuring product safety and efficacy in diverse user conditions.

Keywords: IEC 60118-8 2005, hearing aids testing, electroacoustics, simulated in situ measurement, hearing aid performance, insertion gain, directional microphone measurement, directivity index, acoustic manikin, hearing aid standards, hearing aid quality assurance.