Relation between speech-in-noise threshold, hearing loss and cognition from 40-69 years of age

Abstract

Background: Healthy hearing depends on sensitive ears and adequate brain processing. Essential aspects of both hearing and cognition decline with advancing age, but it is largely unknown how one influences the other. The current standard measure of hearing, the pure-tone audiogram is not very cognitively demanding and does not predict well the most important yet challenging use of hearing, listening to speech in noisy environments. We analysed data from UK Biobank that asked 40-69 year olds about their hearing, and assessed their ability on tests of speech-in-noise hearing and cognition.

Methods and findings: About half a million volunteers were recruited through NHS registers. Respondents completed 'whole-body' testing in purpose-designed, community-based test centres across the UK. Objective hearing (spoken digit recognition in noise) and cognitive (reasoning, memory, processing speed) data were analysed using logistic and multiple regression methods. Speech hearing in noise declined exponentially with age for both sexes from about 50 years, differing from previous audiogram data that showed a more linear decline from <40 years for men, and consistently less hearing loss for women. The decline in speech-in-noise hearing was especially dramatic among those with lower cognitive scores. Decreasing cognitive ability and increasing age were both independently associated with decreasing ability to hear speech-in-noise (0.70 and 0.89 dB, respectively) among the population studied. Men subjectively reported up to 60% higher rates of difficulty hearing than women. Workplace noise history associated with difficulty in both subjective hearing and objective speech hearing in noise. Leisure noise history was associated with subjective, but not with objective difficulty hearing.

Conclusions: Older people have declining cognitive processing ability associated with reduced ability to hear speech in noise, measured by recognition of recorded spoken digits. Subjective reports of hearing difficulty generally show a higher prevalence than objective measures, suggesting that current objective methods could be extended further.

Figure 1. Hearing declines from 40–69 years of age.

(A) UK Biobank: Mean DTT speech reception threshold (SRT; better ear) data, corrected for differences in socio-economic between samples. Exponential functions with an additive constant are fitted to the data. (B) National Study of Hearing (UK [14]): Mean pure tone average (PTA) thresholds (0.5, 1, 2, 4 kHz; better ear). (C) National Health and Nutrition Examination Survey (NHANES, US [16]): Mean PTA thresholds (0.5–4 kHz). Other data points from NIH Toolbox (US, 2011 [18]), Beaver Dam Epidemiology of Hearing Loss Study (US, 1993 [15]), Blue Mountains Hearing Study (Australia, 1997–2000 [17]).

Figure 2. Men report greater difficulty hearing than women.

Prevalence of self-report of (A) hearing difficulty and (B) difficulty hearing speech-in-noise in women and men from 40–70 y.o., corrected for socio-economic.

Figure 3. Cognitive performance declines with age.

Cognitive performance of men and women in the UK Biobank study expressed as a mean standardized (z) score for ease of comparison between different tests.

Figure 4. Better cognition is associated with better hearing.

Relation between mean SRT and mean performance on each cognitive test (by decile of standardized score from 1 = low to 10 = high), all ages (40–69 y.o.) combined.