Spectral edge frequency

The spectral edge frequency or SEF is a measure used in signal processing. It is usually expressed as 'SEF x', which stands for the frequency below which x percent of the total power of a given signal are located. (typically x is in the range 75 to 95.) The spectral edge frequency or SEF is a measure used in signal processing. It is usually expressed as 'SEF x', which stands for the frequency below which x percent of the total power of a given signal are located. (typically x is in the range 75 to 95.) It is more particularly a popular measure used in EEG monitoring, in which case SEF has variously been used to estimate the depth of anesthesia and stages of sleep.