The importance of high-frequency audibility in the speech and language development of children with hearing loss.
OBJECTIVE
To review recent research studies concerning the importance of high-frequency amplification for speech perception in adults and children with hearing loss and to provide preliminary data on the phonological development of normal-hearing and hearing-impaired infants.


METHODS
With the exception of preliminary data from a longitudinal study of phonological development, all of the reviewed studies were taken from the archival literature. To determine the course of phonological development in the first 4 years of life, the following 3 groups of children were recruited: 20 normal-hearing children, 12 hearing-impaired children identified and aided up to 12 months of age (early-ID group), and 4 hearing-impaired children identified after 12 months of age (late-ID group). Children were videotaped in 30-minute sessions at 6- to 8-week intervals from 4 to 36 months of age (or shortly after identification of hearing loss) and at 2- and 6-month intervals thereafter. Broad transcription of child vocalizations, babble, and words was conducted using the International Phonetic Alphabet. A phoneme was judged acquired if it was produced 3 times in a 30-minute session.


METHODS
Preliminary data are presented from the 20 normal-hearing children, 3 children from the early-ID group, and 2 children from the late-ID group.


RESULTS
Compared with the normal-hearing group, the 3 children from the early-ID group showed marked delays in the acquisition of all phonemes. The delay was shortest for vowels and longest for fricatives. Delays for the 2 children from the late-ID group were substantially longer.


CONCLUSIONS
The reviewed studies and preliminary results from our longitudinal study suggest that (1) hearing-aid studies with adult subjects should not be used to predict speech and language performance in infants and young children; (2) the bandwidth of current behind-the-ear hearing aids is inadequate to accurately represent the high-frequency sounds of speech, particularly for female speakers; and (3) preliminary data on phonological development in infants with hearing loss suggest that the greatest delays occur for fricatives, consistent with predictions based on hearing-aid bandwidth.
Stelmachowicz
Patricia G
PG
Boys Town National Research Hospital, Omaha, NE 68131, USA. stelmach@boystown.org
Pittman
Andrea L
AL
Hoover
Brenda M
BM
Lewis
Dawna E
DE
Moeller
Mary Pat
MP
D000162:Acoustics; D000328:Adult; D017668:Age of Onset; D002675:Child, Preschool; D019988:Children with Disabilities; D005260:Female; D006310:Hearing Aids; D006801:Humans; D007223:Infant; D007804:Language Development; D007805:Language Development Disorders / Q000209:etiology; D008297:Male; D019986:Persons with Hearing Disabilities; D011846:Radio Waves; D013067:Speech Perception