Cortical plasticity following short auditory training: A functional near-infrared spectroscopy study

Research has acknowledged the substantial impact of short auditory training on performance enhancements, but the neural mechanisms involved are not fully understood. This study aimed to explore these mechanisms by examining the cortical effects of single-session speech-in-noise (SIN) training with spectrally degraded stimuli, using functional near-infrared spectroscopy (fNIRS). Twenty-four young adults with normal hearing participated in SIN training using noise-vocoded stimuli. Behavioral improvements were evaluated 1-3 days after training. fNIRS recordings were taken before training, 1-3 days after training, and again 1-3 days following the second evaluation, employing a pseudorandom block design with speech, noise, and SIN stimuli. Training led to significant improvements in SIN perception, accompanied by a non-significant trend toward reduced oxygenated blood beta values in the left middle temporal gyrus in response to the trained stimuli across training and testing sessions. This pattern is consistent with the possibility of cortical adaptation and increased neural efficiency during processing of degraded auditory input following brief training, with effects that appear to extend beyond the immediate training session. Further research is needed to determine whether similar short-term training approaches could benefit individuals with hearing or speech perception difficulties.