Hearing Aid OSPL 90 Test Sequence
This sequence follows the ANSI S3.22-1996 standard method for measuring the OSPL curve, the HFA value, and the Max OSPL value for a hearing aid.
This sequence follows the ANSI S3.22-1996 standard method for measuring the OSPL curve, the HFA value, and the Max OSPL value for a hearing aid. An equalized stepped sine sweep from 8 kHz – 200 Hz is played at a level of 90 dBSPL through the anechoic box speaker, and a broadband response curve is analyzed through the hearing aid. Next, the HFA (High Frequency Average) is calculated by averaging the values at three frequencies (1000, 1600, 2500 Hz), and this value is checked with a limit step. The Max OSPL is calculated by finding the maximum point on the broadband response. A limit is also applied to this value.
There are default limit values in the sequence, but the actual numbers have to be modified per the manufacturer’s spec and the tolerances found in the standard. See sections 6.1 and 6.2 of the standard for more information.
- Audio Interface – Listen AudioConnect or similar
- Power Amp – Listen SCAmp or similar
- DC Power Source – Listen DCConnect or similar
- Anechoic Test Box – Bruel & Kjaer 4232 or similar
- 2 cc Coupler – Bruel & Kjaer 4946 or similar
- ½” Reference Mic – B&K 4192 or similar
Hardware Setup and Calibration
- Calibrate the anechoic test box speaker as instructed in the SoundCheck manual.
- Calibrate the reference microphone in the coupler as instructed in the SoundCheck manual.
- Connect output 1 of your audio interface to the input of the amplifier powering the anechoic test box.
- Position your device inside the coupler, and place them at the reference point inside the anechoic test box. Connect the coupler to your microphone power supply.
- Connect the output of the mic supply to the input 1 of your audio interface.
This sequence is included in the Sequences folder of you SoundCheck installation.