Using multimodal imaging techniques to study effects of auditory training in older adults

More difficulty in speech-in-noise (SPiN) perception is experienced by older, than young, adults. Targeted auditory training (AT) is beneficial for improving older adults’ SPiN performances. However, change in brain activity in different neural mechanism consequent on AT remains unclear. The present study uses multimodal techniques that combine functional near-infrared spectroscopy (fNIRS) and systemic physiological measurements to look into neural and physiological changes resulting from AT in older adults (native English speakers over 60 years of age).

Participants receive a pre-training and a post-training fNIRS scanning session. Specifically, they complete a SPiN recognition task under six-talker babbles while the speech reception threshold (SRT) is measured. Subsequently, a neuroimaging experiment is conducted, in which they are instructed to actively attend to short sentences in noisy environments as in the SPiN task but at a fixed SNR level for pre- and post-training sessions. FNIRS signals are recorded over the temporo-frontal areas. Activities are measured at the posterior superior temporal gyrus (pSTG) that reflect responses to speech intelligibility and left inferior frontal gyrus (LIFG) that reflect listening efforts. Connectivity analyses between these two regions are also conducted. Systemic physiology of skin conductance (EDA), heart rate variability (HRV) and respiration rate are simultaneously recorded to provide further measures of listening effort and as control for physiological confounds in fNIRS signals. Between the two scanning sessions, participants receive an adaptive online take-home SPiN perception training that they complete over four weeks.

Differences in behavioral, neural and physiological signals between the pre- and post-training are used to quantify the effects of AT. We anticipate that results of the present study can elucidate the neural mechanisms of how AT contributes to SPiN perception and shed light on future clinical implications for auditory rehabilitation in aging populations.