Aging and difficulty filtering out background noise

Healthy aging is known to be associated with lower abilities to comprehend speech, resulting from poorly understood interplay between sensory and cognitive changes. To further characterize these processes, researchers from Germany and Canada studied neural behavior in younger and older patient groups: 20 younger adults aged 18 to 31 years, and 20 older adults 60-79 years of age.

The study included electroencephalography (EEG) examinations to assess “the dynamic relationship between neural entrainment to stimulus rhythm (during active and passive listening) on the one hand, and task-induced alpha modulations on the other, that is, between rhythmic- and continuous-mode processing during vigilance-style monitoring of a rhythmic stimulus,” according to the authors.

To carry out the study, participants were essentially placed in a simulated “cocktail party” environment. In this background noise, they were asked to hone in on target signals and their EEG results were assessed. Focusing on a voice required participants to filter out background noise.

What the team found was that younger subjects could easily synchronize neural firing with the target signal, thus filtering out the irrelevant noise. However, in older individuals, the neural signals fired in a pattern synchronized with the irrelevant background noise, thus inhibiting their ability to detect the target signals.

Source: Live Science; Henry MJ et al. Aging affects the balance of neural entrainment and top-down neural modulation in the listening brain. Nature Communications. 2017 Jun 27;8:15801.