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.

More