Noisy channels

Definition: Noisy channel refers to a fNIRS channel of insufficient signal quality (i.e. signal-to-noise ratio) that may not or hardly allow to reliably examine hemodynamic activity. Noisy channels can be caused by several factors, including an insufficient light-tissue coupling, defects in the hardware components (e.g. optodes,cables, electrical circuits), or movement artifacts. In fNIRS signal processing, noisy channels are identified by either manual, semi-manual or automatic methods (e.g. by identifying noisy channels through exceeding a specific threshold of the standard deviation of the signal).

Alternative definition:

Synonym: aberrant channels, noisy channels

References:

https://doi.org/10.1364%2FBOE.7.005104

https://doi.org/10.1117/1.NPh.8.1.012101

Related terms: scalp coupling index, peak spectral power, coefficient of variation, spikes, baseline shifts, signal quality, signal calibration, scalp-optode coupling