Short separation channel location impacts the performance of short channel regression in NIRS

► Short separation channel location impacts the performance of the method. ► Systemic physiology is inhomogeneous across the scalp. ► CNR improvement of 50% (HbO) and 100% (HbR) if regressor is located within 1.5 cm. ► Only mild improvement if short channel is located farther than 1.5 cm.