IEC 60118-9:2019

Overview

IEC 60118-9:2019 is an international standard published by the International Electrotechnical Commission (IEC) that defines standardized methods for measuring the performance characteristics of bone conduction hearing aids. This second edition updates and replaces the first edition from 1985, introducing significant technical revisions such as expanding the measurement frequency range to 8,000 Hz for bone coupled devices and including measurement procedures for bone coupled devices using a skull simulator.

Bone conduction hearing aids differ from conventional air conduction hearing aids by transmitting sound via mechanical vibrations to the skull rather than through air vibrations to the ear canal. Due to this fundamental difference, measurement methods must capture both electrical input and mechanical output signals, with an emphasis on vibratory force or force level rather than simply acoustic gain.

The ISO/IEC harmonized approach ensures measurements are practical, reproducible, and consistent across devices, enabling reliable comparisons and data exchange between manufacturers and laboratories under controlled conditions.

Key Topics

• Scope of Measurement Methods
  Covers both transcutaneously coupled bone conduction hearing aids (measured on a mechanical coupler in line with IEC 60318-6) and bone anchored devices measured via a skull simulator.

• Measurement Parameters
  Includes frequency response curves, vibratory force levels, total harmonic distortion, equivalent input noise, battery current, and sensitivity of induction pick-up coils.

• Measurement Setup Requirements
  Specifies recommended measurement enclosures, sound sources, and equipment calibration to ensure minimal interference and unwanted stimuli.

• Conditions for Application
  Defines procedures for applying bone vibrators to mechanical couplers or skull simulators and controlling environmental conditions such as ambient noise, mechanical coupling force, and supply voltage.

• Frequency Range Extension
  Extends measurement capability for bone coupled devices up to 8,000 Hz, enabling more accurate assessment of modern hearing aids with advanced bandwidth.

• Reporting and Uncertainty
  Details how to present measurement data and acceptable maximum permitted uncertainty to maintain standardization and reliability of test results.

Applications

IEC 60118-9:2019 serves as the authoritative guide for manufacturers, test laboratories, and regulatory authorities involved in the design, testing, certification, and quality assurance of bone conduction hearing aids. Key practical benefits include:

• Product Development
  Enables manufacturers to evaluate device performance with reliable, repeatable testing that guides design improvements targeting frequency response, distortion, and electromagnetic compatibility.

• Certification and Compliance
  Supports compliance with international standards and facilitates market access by providing uniform test criteria accepted globally.

• Clinical and Consumer Confidence
  Assures audiologists and end-users that bone conduction hearing aids meet defined performance benchmarks, contributing to better hearing outcomes.

• Research and Innovation
  Provides a standardized framework for academic and industrial research to develop new bone conduction technologies and hybrid hearing solutions.

Related Standards

• IEC 60118-0
  Specifies measurement methods for air conduction hearing aids, complementing IEC 60118-9 by addressing a different hearing aid modality.

• IEC 60318-6
  Defines requirements for mechanical couplers used in testing transcutaneously coupled bone conduction hearing aids.

• IEC 60118 Series
  Encompasses all parts related to hearing aid electroacoustics, covering diverse hearing aid technologies and measurement methods.

• ISO/IEC Directives
  Guides the preparation and drafting of international standards ensuring consistency and harmonization in technical documentation.

Keywords: IEC 60118-9:2019, bone conduction hearing aids, measurement methods, electroacoustics, mechanical coupler, skull simulator, hearing aid testing, vibratory force level, frequency response, hearing aid standards, acoustic measurement, hearing aid performance, international standard.