How large is the individual difference in hearing sensitivity?: Establishment of ISO 28961 on the statistical distribution of hearing thresholds of otologically normal young persons

Abstract

ISO 28961, which describes the statistical distribution of hearing thresholds of otologically normal young persons, was established in 2012. The thresholds are those for pure tones of frontal incidence under binaural listening conditions in a free field. Percentiles of the threshold distribution are calculable as a function of frequency from 20 Hz to 16,000 Hz. This international standard is based on the study results of the present authors, who estimated the form of individual distribution using threshold data in their experiments and those in literature adopted in ISO 226 and ISO 389-7. However, because the results were published separately in four journal papers, users of the standard may encounter difficulty in understanding the process of how the threshold data have been integrated and how the threshold distribution has been determined. Therefore, the authors summarize them in this review paper and present an outline of the threshold distribution estimation so that the standard will be understood correctly and used widely.

Hearing threshold, loudness, and annoyance of infrasonic versus non-infrasonic frequencies

“…Our SDs in the infrasonic range were 4-5 dB (Table S2). The values agreed with the SD of the previous studies [15] and for frequencies above 20 Hz [11].…”

“…We are only aware of one study which has defined EACs extending to infrasonic frequencies [1]. For comparison, Kurakata et al [11] and Subedi et al [21] developed EACs within 1000-18000 Hz and 31.5-80 Hz, respectively. It should be emphasized that high noise annoyance is a predictor of many adverse health effects [26].…”

Can acoustic design accommodate aural diversity?

“…The second set of papers within this theme seek to develop new measurements of above-threshold hearing tasks which can help to predict the diverse outcomes for people with hearing impairments [8] [9]. A third theme concerns the distribution of a specific audiological measurement in a population, most typically pure-tone hearing threshold [10]. The fourth and final theme in the dataset are papers which postdate Drever and which use the term aural diversity in approximately the sense coined by him.…”