Nonlinear frequency compression compensates for hearing loss in frequency ranges where traditional amplification on its own does not provide sufficient benefit.
The effectiveness of Phonak’s proprietary nonlinear frequency compression algorithm, SoundRecover, has been documented for more significant degrees hearing loss (Simpson, Hersbach & McDermott, 2005, 2006; Nyffeler, 2008). The purpose of this study was to test whether SoundRecover provides sufficient benefit for people with mild to moderate hearing loss. Sufficient benefit is defined as whether the person can more easily recognize quiet, high frequency sounds. This study focused particularly on the /s/ sound. To measure consonant identification, a special test, the Adaptive Logatom Test, was designed that is sufficiently sensitive for cases of mild and moderate hearing loss (i.e. phonemes cannot be discerned on the basis of word or sentence context). The Adaptive Logatom Test was administered using adaptive control of the presentation level, and the respective identification thresholds of various consonants in nonsense syllables (logatoms) were recorded. The identification threshold of the /s/ sound clearly improved with SoundRecover. In addition, subjects reported that listening with SoundRecover was more pleasant than listening without it. A summary of this study was previously published in Phonak Field Study News (April 2009). This article provides the entire study, results and discussion.