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Release Time Hearing Aid Test Sequence

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This sequence follows the ANSI S3.22-1996 standard method for testing the release time of AGC (automatic gain control) hearing aids. A 2 kHz sine tone is played at 90 dBSPL for 1 second and then immediately drops to 55 dBSPL for 2 more seconds. A band limited time envelope (1.5-2.5 kHz) is created and then run through a post processing step, which calculates the release time. It does this by calculating the time it takes the device to stabilize within 4 dB of its steady level.

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Measuring Hearing Protection Devices to ANSI S3.19-1974 Standard

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This sequence is used to measure the NRR, or Noise Reduction Rating, of a hearing protection device to the ANSI S3.19-1974 standard. NRR is a numerical representation of the sound attenuation of a device. The sequence first measures the response spectrum of the unoccluded hearing protector test fixture, then makes a second measurement with the hearing protection DUT affixed. A signal generator virtual instrument generates the pink noise stimulus while an RTA virtual instrument simultaneously records the A and C weighted noise spectrums. The unoccluded and occluded measurements are analyzed with a series of post-processing steps according to the ANSI S3.19-1974 standard. The final display shows the NRR numerical value, RTA spectra of the left and right side of the unoccluded and occluded hearing test fixture, average attenuation level of the DUT, and the standard deviation of the DUT on the test fixture.

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