Despite the significant contribution of hearing assistive devices, medications, and surgery to restoring auditory periphery, a large number of people with hearing loss still struggle with understanding speech. This leads many studies on speech perception to move towards the central auditory functions by looking at associated brain activities using macroscopic recording tools such as electroencephalography (EEG). Up until a few years ago, however, limitation has been given to the brain scientists who attempted to investigate speech perception mechanisms using the EEG. In particular, short duration of speech segments has inevitably been used to elicit auditory evoked potential, even though they were too brief to be considered as speech. Today, however, advance in neural engineering and better understanding of neural mechanism have better facilitated brain scientists to perform studies with running stream of continuous speech and expand the scope of EEG studies to include comprehension of more realistic speech envelope. The purpose of this study is to review literatures on neural tracking to speech envelope to discuss it in Audiology perspective. This review article consists of seven subjects including introduction, neural tracking theories, neural tracking measure, signal processing & analysis, literature review on neural tracking associated with hearing loss, application of neural tracking to audiology, and conclusion. We noted that neural tracking has potential to be used in clinical sets to objectively evaluate speech comprehension for people with hearing loss in the future.
MATERIALS AND METHODS