A TECHNICAL COMPARISON OF DIGITAL FREQUENCY LOWERING ALGORITHMS AVAILABLE IN TWO CURRENT HEARING AIDS YURI SOKOLOV: IN CONVERSATION. SPEECH GUARD: PROVIDING AUDIBILITY AND CUES FOR AUDITORY PROCESSING Simply ingenious

Recently two major manufacturers of hearing aids introduced two distinct frequencylowering techniques that were designed to compensate in part for the perceptual effects of highfrequency 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.  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.  The results of the analyses confirmed that each scheme was effective at lowering certain highfrequency 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, considerably different perceptual effects would be expected from these schemes, even when each hearing aid is fitted in accordance with the same audiometric configuration of hearing impairment. In general, these findings reinforce the need for appropriate selection and fitting of sound processing schemes in modern hearing aids to suit the characteristics and preferences of individual listeners. A Technical Comparison of Digital Frequency Lowering Algorithms Available in Two Current Hearing Aids About the Author Hugh J. McDermott is with The Bionic Ear Institute and the Department of Otolaryngology, The University of Melbourne, Victoria, Australia. "Sycle's reports allow me to easily gauge our practice's performance and provide me with the information I need to make strategic business decisions." Jerry Poteet, BC HIS Owner, ClearSound Hearing Sycle simpli es running your practice so you can have more time with your patients. Sycle is today's leading practice management solution in audiology and hearing care. Canadian insurance capabilities built in Drag and drop appointment scheduling Real time reporting Secure access from anywhere Best in class Noah and Quickbooks integration Free training and support Call us today to get started: (888) 885 5155 sycle.net *O er valid until 11:59pm PST on December 31st, 2015. New customers only. Previous Sycle customers do not qualify. NOW availabl e in Canad a! TRY SYCLE NOW AND RECEIVE THE REST OF THE YEAR FOR FREE* Citation: McDermott HJ (2011) A Technical Comparison of Digital Frequency Lowering Algorithms Available in Two Current Hearing Aids. PLoS ONE 6(7) e22358.    The author has no support or funding to report.  The author is an employee of The Bionic Ear Institute and has an honorary appointment in the Department of Otolaryngology, The University of Melbourne, Victoria, Australia. The Bionic Ear Institute (BEI) (www.bionicear.org) is an independent, non profit, research organisation. The author is the originator of Phonak' SoundRecover scheme, as disclosed in Australian Patent Application number 2002300314 "Apparatus And Method For Frequency Transposition In Hearing Aids" There are no other patents, products in development or marketed products to declare. This does not alter the author's adherence to all the PLoS ONE policies on sharing data and materials, as detailed online in the guide for authors.