An Evidence-Based Systematic Review of Amplitude Compression in Hearing Aids for School-Age Children With Hearing Loss

Abstract

Purpose Two clinical questions were developed: one addressing the comparison of linear amplification with compression limiting to linear amplification with peak clipping, and the second comparing wide dynamic range compression with linear amplification for outcomes of audibility, speech recognition, speech and language, and self- or parent report in children with hearing loss. Method Twenty-six databases were systematically searched for studies addressing a clinical question and meeting all inclusion criteria. Studies were evaluated for methodological quality, and effect sizes were reported or calculated when possible. Results The literature search resulted in the inclusion of 8 studies. All 8 studies included comparisons of wide dynamic range compression to linear amplification, and 2 of the 8 studies provided comparisons of compression limiting versus peak clipping. Conclusions Moderate evidence from the included studies demonstrated that audibility was improved and speech recognition was either maintained or improved with wide dynamic range compression as compared with linear amplification. No significant differences were observed between compression limiting and peak clipping on outcomes (i.e., speech recognition and self-/parent report) reported across the 2 studies. Preference ratings appear to be influenced by participant characteristics and environmental factors. Further research is needed before conclusions can confidently be drawn.

An Evidence-Based Systematic Review of Directional Microphones and Digital Noise Reduction Hearing Aids in School-Age Children With Hearing Loss

“…We searched 26 databases (e.g., PubMed, CINAHL, PsycINFO, ERIC) from January to April 2010 using keywords related to hearing loss, children, and amplification (e.g., hearing aid, hearing instrument, amplification, child, frequency compression ). A full list of the searched databases and search terms are included in a concurrent review within this series, McCreery, Venediktov, Coleman, and Leech (2012). We examined reference lists of all full-text articles retrieved from the initial search to identify additional relevant articles.…”

“…We examined reference lists of all full-text articles retrieved from the initial search to identify additional relevant articles. One author looked for articles citing the studies accepted for inclusion (see McCreery et al, 2012) and searched in the EBSCO database for literature published by 26 prolific authors. The overarching search for the series of reviews was initially completed from January to April 2010; however, given the size and scope of the review series as well as the lapse of time with report of results, the search was updated to include studies published through July 2011.…”

“…Studies including participants outside of the target age range were excluded unless the mean age fell within the target age range or if the data could be split for separate analyses. Operational definitions of signal processing strategies and outcomes are included in McCreery et al (2012). Two authors independently applied the inclusion criteria to determine study eligibility based on abstracts.…”

Congenital hearing loss

“…Continued developments in signal processing and increasing miniaturization have increased the performance of hearing aids and their acceptance among patients. 85, 86 For example, the maximum gains for digital in-the-ear, in-the-canal and completely-in-canal aids are about 55–65 dB, 45–55 dB and 35–50 dB, respectively. Nearly all hearing aids are digital and programmable and, therefore, can be customized to the characteristics of the patient’s hearing.…”

Perceptual Implications of Level- and Frequency-Specific Deviations from Hearing Aid Prescription in Children

“…Research with adults has suggested that both inadequate and excessive amplitude compression can negatively impact speech-recognition abilities for listeners who wear HAs (Brennan and Souza, 2009; Jenstad and Souza, 2007). While studies with children suggest that appropriately prescribed amplitude compression can improve speech recognition compared with linear amplification (Jenstad et al, 1999; or see McCreery et al, 2012 for review), inadequate or excessive amplitude compression might result in differences in audibility for speech that are only apparent when assessing multiple input levels. Differences in audibility across input levels could negatively affect perception in children with hearing loss.…”