Objective: There is little information on speech and language development in pre-school children with mild, moderate or severe hearing impairment. The primary aim of the study is to establish a reference material for clinical use covering various aspects of speech and language functions and to relate test values to pure tone audiograms and parents' judgement of their children's hearing and language abilities.
Methods: Nine speech and language tests were applied or modified, both classical tests and newly developed tests. Ninety-seven children with normal hearing and 156 with hearing impairment were tested. Hearing was 80 dB HL PTA or better in the best ear. Swedish was their strongest language. None had any additional diagnosed major handicaps. The children were 4-6 years of age. The material was divided into 10 categories of hearing impairment, 5 conductive and 5 sensorineural: unilateral; bilateral 0-20; 21-40; 41-60; 61-80 dB HL PTA. The tests, selected on the basis of a three component language model, are phoneme discrimination; rhyme matching; Peabody Picture Vocabulary Test (PPVT-III, word perception); Test for Reception of Grammar (TROG, grammar perception); prosodic phrase focus; rhyme construction; Word Finding Vocabulary Test (word production); Action Picture Test (grammar production); oral motor test.
Results: Only categories with sensorineural loss showed significant differences from normal. Word production showed the most marked delay for 21-40 dB HL: 5 and 6 years p<0.01; for 41-60 dB: 4 years p<0.01 and 6 years p<0.01 and 61-80 dB: 5 years p<0.05. Phoneme discrimination 21-40 dB HL: 6 years p<0.05; 41-60 dB: 4 years p<0.01; 61-80 dB: 4 years p<0.001, 5 years p<0.001. Rhyme matching: no significant difference as compared to normal data. Word perception: sensorineural 41-60 dB HL: 6 years p<0.05; 61-80 dB: 4 years p<0.05; 5 years p<0.01. Grammar perception: sensorineural 41-60 dB HL: 6 years p<0.05; 61-80 dB: 5 years p<0.05. Prosodic phrase focus: 41-60 dB HL: 5 years p<0.01. Rhyme construction: 41-60 dB HL: 4 years p<0.05. Grammar production: 61-80 dB HL: 5 years p<0.01. Oral motor function: no differences. The Word production test showed a 1.5-2 years delay for sensorineural impairment 41-80 dB HL through 4-6 years of age. There were no differences between hearing-impaired boys and girls. Extended data for the screening test [E. Borg, A. Risberg, B. McAllister, B.M. Undemar, G. Edquist, A.C. Reinholdsson, et al., Language development in hearing-impaired children. Establishment of a reference material for a "Language test for hearing-impaired children", Int. J. Pediatr. Otorhinolaryngol. 65 (2002) 15-26] are presented.
Conclusions: Reference values for expected speech and language development are presented that cover nearly 60% of the studied population. The effect of the peripheral hearing impairment is compensated for in many children with hearing impairment up to 60 dB HL. Above that degree of impairment, language delay is more pronounced, probably due to a loss of acuity. The importance of central cognitive functions, speech reading and signing for compensation of peripheral limitations is pointed out.