The principal objective of this study was to describe speech reception thresholds in noise (SRTTn, i.e., the signal-to-noise ratio corresponding to 50% intelligibility) and self-reported hearing disability in a general adult population. A secondary objective was to investigate to what extent the functional measurements could be predicted on the basis of the self-reported data.
The sample consisted of 1086 subjects over 60 yr of age who participated in the Longitudinal Aging Study Amsterdam and 128 younger adults, mainly between 20 and 30 yr of age. Subjects were given a diotic speech-in-noise test by telephone to estimate the SRTTn and filled in a questionnaire to allow determination of the self-reported hearing disability. The SNR loss (signal-to-noise ratio loss), defined as the amount by which the measured SRTTn exceeds that for subjects with normal hearing, was determined and classified in three hearing-status categories: good, insufficient, and poor.
The median SNR loss for the 60- to 64-year age group was 2.2 dB for men and 1.2 dB for women. The corresponding figures for the 80- to 84-year age group were 5.0 dB and 3.6 dB, respectively. Only 42% of the subjects with poor hearing possessed hearing aids. A single question from the self-reported hearing disability questionnaire could be used to predict the hearing-status category corresponding to the results of the speech-in-noise test correctly in 62% of the cases. Use of all five of the questions from the questionnaire allowed 69% of the subjects to be classified correctly. There is a strong effect of age on the relation between reported hearing disability and SNR loss.
SNR loss is a common disability in people aged 60 yr or more. Relatively few people with significant SNR loss have hearing aids. Screening for SNR loss with a speech-in-noise test performed by telephone is preferable to use of a short questionnaire, even when an age-specific scoring method is applied.