This standard describes techniques used to measure hearing aids under simulated conditions of real
ear use. The need for such a standard arises from the importance of including the acoustical
variations in the performance data that are caused when hearing aids are worn. For example, the
diffraction of the body and head of a hearing aid wearer on incident sound can significantly change the
input sound pressure to a hearing aid microphone. For the purpose of these measurements, a
suitable manikin and ear simulator are used to represent a typical hearing aid wearer. Acoustical
requirements of the test space as well as how the manikin is positioned with respect to the sound
source are given. Two methods are presented by which to control the level of the incident sound field
at the location of the hearing aid on the manikin during the testing. Procedures are provided to obtain
the insertion gain, or the amount by which the hearing aid changes the eardrum sound pressure in the
ear simulator of the manikin relative to that in the unaided condition. Procedures are also provided to
obtain the directional response of the manikin as a function of azimuth and elevation of the sound
source, with and without the assistance of a hearing aid, and to calculate the directivity index from the
directional response. The gains obtained with a hearing aid are distinguished by whether the unaided
manikin gain is included in (simulated real-ear aided gain) or subtracted from (simulated insertion gain)
the aided gain.
| ANSI : | ANSI Approved |
| Number of Pages : | 50 |
| Published : | 12/16/2004 |
