IEC 60118-9:2019 specifies methods for the measurement of bone conduction hearing aid characteristics. The methods described will produce a suitable basis for the exchange of information or for direct comparison of the electroacoustical characteristics of bone conduction hearing aids. These methods are chosen to be practical and reproducible and are based on selected fixed parameters. The results obtained by the methods specified in this document express the performance under the conditions of measurement; however, the performance of the hearing aid under practical conditions of use will depend upon a number of factors (e.g. effective load impedance, environmental conditions, acoustical environment, etc.). This document defines methods of measurement of characteristics of bone conduction hearing aids both for • transcutaneously coupled devices measured on a mechanical coupler, meeting the requirements of IEC 60318-6, and • bone coupled/bone anchored devices measured on a skull simulator. IEC 60118-9:2019 cancels and replaces the first edition published in 1985. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) includes bone coupled devices measured on a skull simulator; b) measurement frequency range increased to 8 000 Hz for bone coupled devices.