Effects of extended-range frequency-response amplification in hearing aids.

Spondaic threshold (ST), loudness-discomfort level (LDL) for speech-shaped noise, and NU6 speech scores at 50 db HL (in quiet and at S/N = 0) were taken from 8 adults aged 34-80 yrs, with HTLs less than or equal to 20 db at .25-1 kc/s but with moderate-to-severe sensorineural hearing impairments beginning above 1 kc/s. S listened monaurally to a loudspeaker in an audiometric booth wearing no hearing aid in the test ear or one of 2 all-in-the-ear aids differing only in frequency response (.38-5 kc/s vs .30-7 kc/s). Gain was not changed during the experiment. Extended-range amplification for the total group was not beneficial, nor was it found generally beneficial even when speech scores in quiet or in noise for a group of 4 Ss with impairments beginning above 2 kc/s were compared with those for a group of 4 Ss with impairment beginning below 2 kc/s. However, the narrower-band aid revealed significant (0.10 level of confidence) amplification effects on speech scores compared with the unaided condition.