Acoustic trauma caused by the telephone. Report of two cases

Two patients with acoustic trauma resulting from the use of telephones have been evaluated. Both patients used a particular type of telephone which had the ringing device located in the ear receiver and no automatic gain control in the circuit. The output of the bell recorded on one of these telephones was in the 139-dB range on the A scale. The auditory insult resulted, in the case involving a cord-type telephone, from the transmission of a loud, extraneous sound probably due to a misfunction of the circuit and, in the second case, from the patient holding his cordless telephone against his ear when ringing occurred.