The Effect of Nonlinear Frequency Compression on Speech Recognition in Noise for Hearing-Impaired Listeners with Hearing Aids / 听力学及言语疾病杂志

ABSTRACT

Objective The purpose of this study is to investigate the effects of activating NLFC (nonlinear frequency compression, NLFC) on speech recognition in noise for listeners with high-frequency hearing loss.The results from the present study will provide guidance for clinical practice of fitting hearing aids to hearing impaired listeners.Methods Twenty-five hearing-impaired listeners participated in this study.They all wore binaural hearing aids.The subjects were divided into two groups based on whether NLFC was used in their hearing aids or not.Subjects who used NLFC were in group A and the others who used conventional process (CP) instead of NLFC were in group B.Both groups were tested with speech recognition in noise under the conditions of NLFC and CP.The statistical method of paired samples test was conducted to assess the effect of NLFC and CP on speech recognition in noise.Results The average performance in group A was 82.33%±16.06% and 76.70%±18.08 with NLFC and CP, respectively (P<0.01).It suggested that NLFC had a significant effect on subjects' speech recognition in noise in group A.However, the average performance in group B was 83.04%±12.56% and 81.79%±20.07% with NLFC and CP, respectively (P=0.19).It suggested that there was no significant effect of NLFC on subjects' speech recognition in noise in group B.The average high frequency threshold in group A was 53.54±7.30 and 57.01±6.81 dB SPL with NLFC and CP, respectively(P<0.01).And the average high frequency threshold in group B was 57.42±8.38 and 61.21±7.42 dB SPL with NLFC and CP, respectively(P=0.03).The significant correlativity in statistics on the speech recognition score in noise(y) verse the difference of high frequency hearing threshold (4,6,8 kHz) under the condition of NLFC activated and deactivated (x) in the subjects was y=1.21x-0.40 (r=0.63, t=3.89, P=0.007).Conclusion NLFC technology is beneficial to improving hearing aid users' audibility of high frequency and speech recognition in noise.Certain acclimatization period may be necessary to maximize the potential benefit for NLFC.