Effect of stimulus bandwidth on auditory skills in normal-hearing and hearing-impaired children.
OBJECTIVE
Previous studies from our laboratory have shown that a restricted stimulus bandwidth can have a negative effect upon the perception of the phonemes /s/ and /z/, which serve multiple linguistic functions in the English language. These findings may have important implications for the development of speech and language in young children with hearing loss because the bandwidth of current hearing aids generally is restricted to 6 to 7 kHz. The primary goal of the current study was to expand our previous work to examine the effects of stimulus bandwidth on a wide range of speech materials, to include a variety of auditory-related tasks, and to include the effects of background noise.


METHODS
Thirty-two children with normal hearing and 24 children with sensorineural hearing loss (7 to 14 yr) participated in this study. To assess the effects of stimulus bandwidth, four different auditory tasks were used: 1) nonsense syllable perception, 2) word recognition, 3) novel-word learning, and 4) listening effort. Auditory stimuli recorded by a female talker were low-pass filtered at 5 and 10 kHz and presented in noise.


RESULTS
For the children with normal hearing, significant bandwidth effects were observed for the perception of nonsense syllables and for words but not for novel-word learning or listening effort. In the 10-kHz bandwidth condition, children with hearing loss showed significant improvements for monosyllabic words but not for nonsense syllables, novel-word learning, or listening effort. Further examination, however, revealed marked improvements for the perception of specific phonemes. For example, bandwidth effects for the perception of /s/ and /z/ were not only significant but much greater than that seen in the group with normal hearing.


CONCLUSIONS
The current results are consistent with previous studies that have shown that a restricted stimulus bandwidth can negatively affect the perception of /s/ and /z/ spoken by female talkers. Given the importance of these phonemes in the English language and the tendency of early caregivers to be female, an inability to perceive these sounds correctly may have a negative impact on both phonological and morphological development.
Stelmachowicz
Patricia G
PG
Boys Town National Research Hospital, Omaha, NE 68131, USA. stelmach@boystown.org
Lewis
Dawna E
DE
Choi
Sangsook
S
Hoover
Brenda
B
D000293:Adolescent; D002648:Child; D002663:Child Language; D003051:Cochlea / Q000503:physiopathology; D005260:Female; D006311:Hearing Disorders / Q000175:diagnosis* / Q000453:epidemiology; D006319:Hearing Loss, Sensorineural / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D006801:Humans; D008297:Male; D008570:Memory, Short-Term; D010700:Phonetics; D012720:Severity of Illness Index; D013063:Speech Discrimination Tests; D013067:Speech Perception