What is PD IEC/TS 62886- Hearing aids about?
PD IEC/TS 62886 is a safety standard on the method for measuring electroacoustic performance up to 16 kHz. PD IEC/TS 62886, which is a Technical Specification, describes a coupler and measurement methods to characterize the electroacoustic performance of hearing aids and insert earphones primarily in the range of 8 kHz to 16 kHz.
The coupling plate for the test described in PD IEC/TS 62886 includes a source and a control microphone. This assembly can be attached to the reference cavity and the coupler under test. The control microphone measures the sound pressure in the reference cavity and in the coupler under test. The sound source input signal shall be the same for both measurements.
Who is PD IEC/TS 62886- Hearing aids for?
PD IEC/TS 62886 on the method for measuring electroacoustic performance is relevant to:
- Manufacturers of hearing aids
- Manufacturers of microphones
- Manufacturers of the coupler
- Audiologists
- Medical personnel
- Testing authorities
Why should you use PD IEC/TS 62886- Hearing aids?
Advancement in hearing aid design makes it possible to increase the bandwidth of hearing aids up to 16 kHz.
PD IEC/TS 62886 assists the user with the occluded ear simulator is designed for a specific insertion depth of the ear mould, which is associated with a half-wavelength λ/2 resonance at about 13,5 kHz. This half-wavelength resonance degrades the reproducibility of measurement results in that frequency range and harmonic distortion measurements made at corresponding multiples of the resonance frequency. The effective internal volume of the coupler described in PD IEC/TS 62886 is 0,4 cm3, which is small enough not to produce any resonance in the frequency range below 16 kHz. The frequency response of the magnitude of acoustic impedance follows a pattern of a capacitive load up to about 30 kHz. With a sufficiently high source impedance and a sufficiently small coupling volume, the 0,4 cm3 coupler produces an approximately 14 dB higher output at 1 kHz in comparison to data obtained with the 2 cm3 coupler. The coupler described in PD IEC/TS 62886 allows the characterization of hearing aids and transducers, including the verification of simulation models, up to 16 kHz. 0,4 cm3 is also approximately the residual volume of the ear canal when fitted with a CIC hearing aid (completely-in-the-canal) hearing aid, making the coupler particularly useful for the application. In combination with an appropriate real-ear probe microphone measurement, the 0,4 cm3 coupler enables the derivation of real-ear to coupler difference (RECD) up to 16 kHz.
Overall, PD IEC/TS 62736 is useful as it specifies the coupler that consists of a cylindrical cavity whose effective volume is nominally 400 mm3. The base of the cylindrical cavity contains the diaphragm of a microphone or a microphone with an adaptor.
