Speech Perception Decline in Middle Age Linked to Changes in Brain Activity

Previously, research on speech perception decline in middle-aged adults has focused on how the functioning of the ears and the brainstem diminishes with age; however, a recent study, Reduced Neural Distinctiveness of Speech Representations in the Middle-Aged Brain, examines how changes in brain activity in the cortex also influence how middle-aged people interpret phonemes — or speech sounds. The team included Aravind Parthasarathy, PhD, of Pitt’s Department of Communication Science and Disorders.

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The study used data from a larger and more general study on speech perception in middle age. In total, there were 44 participants whose first language was English, comprising 24 younger individuals (18-25 years old) and 20 middle-aged individuals (40-54 years old). First, the participants’ ear health and brainstem responses were assessed, displaying that most participants had normal hearing. Then, a WIN (Words in Noise) test was conducted to evaluate how participants understood language in various background noises. The study also included a continuous noise test, which involved listening to an audio recording and answering comprehension questions. Participants’ brain activity during the continuous speech was recorded and analyzed using EEG.

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The results showed that middle-aged brains had more difficulty accurately predicting phonemes and were less certain of their interpretations than younger adults. Middle-aged brains also exhibited delayed response times, more dispersed brain activity, and weaker discrimination between speech sounds and phonemes. Finally, despite passing the hearing tests, the middle-aged participants showed cochlear nerve damage (CND) signs. The study concluded that these differences in the middle-aged participants’ speech perception cannot be fully explained by hearing loss and are likely related to changes in the brain.

Ultimately, the study highlights the importance of considering changes in the cortex when investigating the causes of speech perception decline in middle-aged adults.

Read the full study here.