Extended bandwidth nonlinear frequency compression in Mandarin-speaking hearing-aid users.

Abstract

The high frequency information of consonant messages is important for recognition of speech. Recently, the nonlinear frequency compression (NLFC) technique has been shown to improve the speech perception in patients with high frequency hearing loss. In Mandarin, seven consonants are located over 10-16kHz. Extended-bandwidth (EB) NLFC may provide an additional benefit for recognition of Mandarin words. The purpose of this study was to explore the effects of NLFC and EB-NLFC on Mandarin word recognition in patients with high frequency hearing loss. Fourteen native Mandarin-speaking adult patients, aged 20-65 years with bilateral, moderate to severe, sensorineural hearing loss, specifically high frequency hearing loss were included in single-blind randomized study. The assessment tools included the Mandarin Monosyllable Recognition Test (MMRT), Mandarin Hearing in Noise Test (MHINT), and International Outcome Inventory for Hearing Aids (IOI-HA) and sound quality scale of the hearing aids. The patients were tested under unaided condition, after which they were randomly assigned to wear NLFC and EB-NLFC hearing aids, alternatively, in a crossover fashion. After each 4-week block, the patients were tested again to obtain the test outcomes. Patients with hearing aids with EB-NLFC had a significantly better word and consonant recognition using the MMRT (p<0.05). The MHINT was better for the EB-NLFC group without significant differences. The EB-NLFC group had better scores in both the IOI-HA and sound quality scale but not statistically significant. Patients with high-frequency hearing loss may benefit more from using EB-NLFC for word and consonant recognition; however, the improvement was small under a noisy listening environment. The subjective questionnaires did not show significant benefit of EB-NLFC either.