Hearing aid low frequency cut: effect on Mandarin tone and vowel perception in normal-hearing listeners.

OBJECTIVE To investigate the impact of low frequency cuts (LCs) in hearing aid frequency response on Mandarin tone and vowel perception at varying signal-to-noise ratios (S/N ratios). PATIENTS AND METHODS Four LC conditions were reviewed, using a programmable, behind-the-ear hearing aid: no LC (NoLC), a 6-dB/octave LC (LC6), a 12-dB/octave LC (LC12), and an 18-dB/octave LC (LC18). Five S/N ratios for speech to white noise were selected: +10 dB, +5 dB, 0 dB, -5 dB and -10 dB. Speech and noise stimuli were presented to 25 normal-hearing, native Mandarin-speaking listeners monaurally. RESULTS Tone and vowel recognition scores were high for subjects in all experimental conditions except for LC18 and S/N -10 dB. The LCs had minimal impact on tone perception in the positive S/N and S/N 0 conditions. Significant differences for tone recognition were found between the NoLC and LC6, and the LC6 and LC18 conditions with negative S/N ratios. Significant differences in vowel recognition were observed between the LC12 and LC18 settings, at all S/N conditions. CONCLUSION LC hearing aid settings may negatively impact on vowel recognition, and may adversely affect Mandarin tone recognition in adverse noise conditions, in normal-hearing listeners.