Background: When fitting hearing aid as a compensatory device for an impaired cochlea in a patient with sensorineural hearing loss (HL), it is needed to the effective and efficient frequency response would be selected regarding providing the patient's perfect speech perception. There is not any research about the effects of frequency modifications on speech perception in patients with HL regarding the cochlear desensitization. The effect (s) of modifications in frequency response of hearing aid amplification on the results of acceptable noise level (ANL) test is the main aim of this study.
Materials and Methods: The amounts of ANL in two conditions of linear amplification (high frequency emphasis [HFE] and mid frequency emphasis [MFE]) were measured. Thirty-two male subjects who participated in this study had the moderate to severe sensorineural HL.
Results: There was not any significant difference between ANL in linear amplification of hearing aid with HFE frequency response and ANL in linear amplification of hearing aid with MFE frequency response.
Conclusion: The gain modification of frequency response not only does not affect the patient's performance of speech intelligibility in ANL test. This indicates that we need to note to the cochlear desensitization phenomenon when fitting hearing aid as a compensatory device for an impaired cochlea in a patient. The cochlear desensitization has not been considered properly in hearing aid fitting formula which is needed to be explored more about the bio-mechanisms of impaired cochlea.
Duquesnoy AJ. Effect of a single interfering noise or speech source upon the binaural sentence intelligibility of aged persons. J Acoust Soc Am 1983;74:739-43.
Baer T, Moore BC. Effects of spectral smearing on the intelligibility of sentences in the presence of interfering speech. J Acoust Soc Am 1994;95:2277-80.