Tests for those suspected of feigning deafness
In medico-legal practice, feigned deafness is sometimes encountered, both in personal injury claims (especially where claimants are seeking compensation for alleged industrial deafness) and in medical negligence cases. Unreliability of the audiogram may be a good indicator of feigned deafness, as may an audiogram which is incompatible with the subject’s conversational ability without the use of lip-reading or a hearing aid. Where the suspicion is of feigned deafness affecting both ears, the most reliable test is cortical ERA at three or four frequencies. When the Cera test reveals hearing better than that indicated by the subject, and when this is explained, a further pure-tone audiogram often proves similar to the Cera result. Prior to the availability of Cera testing, other tests of less accuracy were used, including delayed-speech feedback, where the subject read a passage into a microphone while his own speech was fed back to him with a short time delay, at a volume which his audiogram suggested he should not be able to hear. Almost everyone who listens to delayed-speech feedback rapidly develops broken and chaotic speech, and this could be used to estimate the true speech threshold, although it is now only of historical interest.