Effects of Three Amplification Strategies on Speech Perception by Children With Severe and Profound Hearing Loss Josephine E. Marriage, Brian C. J. Moore, Michael A. Stone, and Thomas Baer Objective: Traditionally in the United Kingdom, children with severe and profound hearing loss have been fitted with linear, analog hearing aids. Fast-acting, wide-dynamic-range compression (WDRC) has been shown to give better discrimina- tion of speech than linear amplification for moder- ately hearing-impaired young adults. For severe and profound hearing losses, higher compression ratios are needed. The resultant distortion of the temporal envelope and reduced modulation depth may offset improvements in audibility offered by WDRC. In this study, speech recognition and dis- crimination were assessed for severely and pro- foundly hearing-impaired children, using three dif- ferent amplification strategies, including WDRC. Design: Fifteen children (ages 7 to 15 yr) with severe and profound hearing loss were fitted bilaterally with high-power, multichannel compression hear- ing aids, incorporating one of three different ampli- fication strategies: linear with peak clipping, linear with compression limiting, or WDRC. Output re- sponses were matched to Desired Sensation Level (DSL i/o) targets. The children wore hearing aids programmed with each of the amplification strate- gies in turn, for at least 1 wk, in a counterbalanced order across children. After using a particular am- plification strategy for at least 1 wk, speech percep- tion tests were carried out. Results: Speech scores on closed-set testing for the profound group showed significant benefit for WDRC over the other two algorithms. None of the other results showed a statistically significant ef- fect of algorithm on speech performance. Conclusions: WDRC amplification sometimes led to better performance than linear amplification with peak clipping or output limiting, and it never led to poorer performance. Therefore, it appears to be safe to use well-designed WDRC for hearing-im- paired children with severe or profound hearing loss. (Ear & Hearing 2005;26;35– 47) Sensorineural hearing loss is often associated with loudness recruitment, an abnormally rapid growth of loudness level with increasing sound level (Fowler, 1936; Hood, 1972; Moore, 2004). Recruit- ment is thought to be at least partly related to reduced compressive nonlinearity on the basilar membrane, produced by loss of outer hair cell func- tion (Moore, 1998; Ruggero & Rich, 1991; Yates, 1990). The effect of recruitment is represented on the audiogram by the reduced range between hear- ing thresholds and uncomfortable loudness levels. With linear hearing aids, the same amount of gain is applied to incoming sounds of a given fre- quency regardless of the level of sound entering the hearing aid, up to the maximum output level of the hearing aid. The effect of linear amplification is that at a set volume, weak sounds may have insufficient gain to be audible to the listener but intense sounds may be uncomfortably loud. An alternative ap- proach is to use hearing aids with wide-dynamic- range compression (WDRC), which give more gain for weak sounds than for intense sounds. WDRC systems typically have short attack and release times, so the gain changes rapidly with changes in level of the incoming sound. The aim is to make weak sounds audible without stronger sounds being made uncomfortably loud. In this way, WDRC com- presses more of the speech spectrum into the resid- ual hearing range, giving increased audibility and comfort, and making loudness perception more sim- ilar to normal (Villchur, 1973). Research on the benefits of WDRC relative to linear amplification, using adult subjects, has given mixed results; for reviews, see Dillon (1996), Moore (1998), and Souza (2002). However, several studies have demonstrated benefits in user satisfaction and performance from WDRC for adult listeners with mild and moderate extents of hearing loss (Lau- rence, Moore, & Glasberg, 1983; Moore, Johnson, Clark, & Pluvinage, 1992; Yund & Buckles, 1995), and WDRC is widely used in modern hearing aids for adults. In cases of severe and profound sensorineural hearing loss, the dynamic range between hearing thresholds and uncomfortable loudness levels is typ- ically narrower than for mild and moderate impair- ments; hence, higher compression ratios (CR) are Department of Experimental Psychology, University of Cam- bridge, Cambridge, United Kingdom (J.E.M., B.C.J.M., M.A.S., T.B.); and Children’s Hearing Evaluation and Amplification Re- source, Royston, United Kingdom (J.E.M.). 0196/0202/05/2601-0035/0 • Ear & Hearing • Copyright © 2005 by Lippincott Williams & Wilkins • Printed in the U.S.A. 35