The attack and release times were measured on each of three samples of 27 different models of compression-type hearing aids using the test conditions specified in ANSI Standard S3-22 (1976). The results indicate that almost all of the hearing aids tested have attack times less than or equal to 10 ms. A little more than half of the hearing aids had release times of 50 ms or less. The range of the attack times varied from 1 to 23 ms and the release times from 5–600 ms.