THE POSSIBILITY of acoustic trauma produced by prolonged use of a powerful hearing aid has been considered in the past (Harford and Markle, 1955;1 Kinney, 1961;2 Naunton, 1957;3 and Sataloff, 19614). Harford and Markle (1955) reported on a case in which the used ear demonstrated threshold shifts after hearing aid usage; when the aid was switched to the other ear, or its use discontinued, the hearing returned to its former level. Sataloff (1961) reported on a similar case. Two larger-scale studies have explicitly investigated this phenomenon, with contradictory results. Naunton (1957) compared the hearing in the used ears with the nonused ears of 120 subjects who wore aids issued by the British government. Not only did he find no evidence of further decrease in hearing in the used ear, but he reported a tendency for the used ear to demonstrate an improvement in hearing. (It should