[Hearing of the mentally retarded living at home].

The present article was undertaken to illustrate the frequency of defective hearing in adult mentally retarded persons living in their homes in the Municipality of Copenhagen. The investigation concerns 115 persons, 57 men and 58 women with an average age of 38 years, range 20-79 years. At the time of the investigation, the persons examined constituted 26% of the total population of adult mentally retarded persons living at home in the Municipality of Copenhagen. The investigation revealed that 5% experienced problems in hearing in quiet surroundings while 15% had hearing problems with background noise. On the basis of pure tone audiometry, normal hearing was found in 60% (less than or equal to 20% dB HL) with frequency criterion including 4 kHz, while 67% (77/115) were found to have normal hearing without including 4 kHz in the frequency criterion. In other words, 40%/33% had defective hearing and were therefore outside the normal range. In order to assess the presence of defective hearing, the limit of greater than or equal to 25 dB HL in the ear with best hearing and the frequency criterion with or without 4 kHz, respectively, was established. On the basis of these criteria a reduction of hearing in the best ear of 30%/24% was found. the investigation revealed, in addition, that at least 17% should have been treated with hearing aids but only one of the persons examined had a hearing aid which was, however, not in use. (ABSTRACT TRUNCATED AT 250 WORDS)