a technical comparison of digital frequency-lowering algorithms available in two current hearing aids技术的比较数字frequency-lowering算法可用两个当前助听器.pdfVIP

A Technical Comparison of Digital Frequency-Lowering Algorithms Available in Two Current Hearing Aids Hugh J. McDermott* The Bionic Ear Institute and The Department of Otolaryngology, The University of Melbourne, Victoria, Australia Abstract Background: Recently two major manufacturers of hearing aids introduced two distinct frequency-lowering techniques that were designed to compensate in part for the perceptual effects of high-frequency hearing impairments. The Widex ‘‘Audibility Extender’’ is a linear frequency transposition scheme, whereas the Phonak ‘‘SoundRecover’’ scheme employs nonlinear frequency compression. Although these schemes process sound signals in very different ways, studies investigating their use by both adults and children with hearing impairment have reported significant perceptual benefits. However, the modifications that these innovative schemes apply to sound signals have not previously been described or compared in detail. Methods: The main aim of the present study was to analyze these schemes’technical performance by measuring outputs from each type of hearing aid with the frequency-lowering functions enabled and disabled. The input signals included sinusoids, flute sounds, and speech material. Spectral analyses were carried out on the output signals produced by the hearing aids in each condition. Conclusions: The results of the analyses confirmed that each scheme was effective at lowering certain high-frequency acoustic signals, although both techniques also distorted some signals. Most importantly, the application of either frequency-lowering scheme would be expected to improve the audibility of many sounds having salient high-frequency components. Nevertheless, c