Cordless Telephones: A Threat to Hearing

Abstract

Several patients with documented permanent sensorineural hearing losses secondary to the use of cordless telephones have been evaluated. In the interests of saving space and weight, these units have the ear receiver double as the ringing or bell device. The output of the bell on all of the units we have tested to date has been in the 140-dB range on the A scale. In each instance, the patient held the telephone against the ear when ringing occurred, and in three instances a loud extraneous crack was transmitted. Unlike regular cord-type telephones, these devices have no automatic gain control in the receiver circuit.

Acoustic Trauma Caused by the Telephone

“…The midfrequency sensorineural hearing loss observed in both patients resembles the findings obtained in most of Singleton's pa tients [1] emphasizing that a characteristic hearing loss results from this particular type of acoustic trauma. One case of significant loss in discrimination score without any sig nificant change in pure-tone audiometry has been reported [3].…”

“…For this reason, these tele phones should be prohibited. Unlike the pa tients of Singleton et al [1] or Orchick et al [2], our 2 patients have fortunately recov ered normal hearing; however, such a favor able outcome is not always predictable and, at the present time, no treatment is known for reestablishing normal hearing after acoustic trauma.…”

“…There is no limiting circuit or automatic gain control either in the ringing device or in the earpiece transducer. Singleton et al [1] reviewed 33 cases of hearing loss due to acoustic trauma from cordless telephones, cases collected either by him or by other members of the American Academy of Otolaryngology-Head and Neck surgery (AAO-HNS). In 30 pa tients the auditory insult resulted from the individual picking up the telephone when it was ringing and placing it to his ear without switching to the 'talk' mode.…”

Predicting mechanical damage to the organ of Corti

“…Unfortunately those devices used the same speaker to produce the ringing signal and the speech message. The result was that some people who had the phone at their ear when the relatively intense ringing signal was present suffered PTS from that exposure (Orchik et al, 1987(Orchik et al, , 1985Singleton et al, 1984;Schumaier, 1986). It would be reasonable to conclude, for purposes of clinical application, that any noise, whether impulsive or continuous, if sufficiently intense could produce a PTS with milliseconds to seconds of exposure.…”

Noise exposure from leisure activities: A review

“…Several studies (Singleton et al, 1984;Gerling and Jerger, 1985;Orchik et al, 1985Orchik et al, , 1987 have concluded that cordless telephones pose a significant risk for producing acoustic trauma. These conclusions are based upon spectral analysis of the ring signal of several cordless telephones, which indicated sound-pressure levels of approximately 140 dB, and case reports from individuals who have sustained permanent hearing losses after single exposure incidents.…”