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ObjectiveA systematic review was conducted to identify and quality assess how studies published since 1999 have measured and reported the usage of hearing aids in older adults. The relationship between usage and other dimensions of hearing aid outcome, age and hearing loss are summarised.Data sourcesArticles were identified through systematic searches in PubMed/MEDLINE, The University of Nottingham Online Catalogue, Web of Science and through reference checking. Study eligibility criteria: (1) participants aged fifty years or over with sensori-neural hearing loss, (2) provision of an air conduction hearing aid, (3) inclusion of hearing aid usage measure(s) and (4) published between 1999 and 2011.ResultsOf the initial 1933 papers obtained from the searches, a total of 64 were found eligible for review and were quality assessed on six dimensions: study design, choice of outcome instruments, level of reporting (usage, age, and audiometry) and cross validation of usage measures. Five papers were rated as being of high quality (scoring 10–12), 35 papers were rated as being of moderate quality (scoring 7–9), 22 as low quality (scoring 4–6) and two as very low quality (scoring 0–2). Fifteen different methods were identified for assessing the usage of hearing aids.ConclusionsGenerally, the usage data reviewed was not well specified. There was a lack of consistency and robustness in the way that usage of hearing aids was assessed and categorised. There is a need for more standardised level of reporting of hearing aid usage data to further understand the relationship between usage and hearing aid outcomes.

The effect of interaural correlation ͑͒ on the loudness for noisebands was measured using a loudness-matching task in naïve listeners. The task involved a sequence of loudness comparisons for which the intensity of one stimulus in a given comparison was varied using a one-up-one-down adaptive rule. The task provided an estimate of the level difference ͑in decibels͒ for which two stimulus conditions have equal loudness, giving measures of loudness difference in equivalent decibel units ͑dB equiv ͒. Concurrent adaptive tracks measured loudness differences between =1, 0, and −1 and between these binaural stimuli and the monaural case for various noisebands. For all noisebands, monaural stimuli required approximately 6 dB higher levels than = 1 for equal loudness. For most noisebands, = 1 and = −1 were almost equal in loudness, with = −1 being slightly louder in the majority of measurements, while = 0 was about 2 dB equiv louder than =1 or = −1. However, noisebands with significant high-frequency energy showed smaller differences: for 3745-4245 Hz, = 0 was only about 0.85 dB equiv louder than = Ϯ 1, and for 100-5000 Hz it was non-significantly louder ͑perhaps 0.7 dB equiv ͒.