What type of waveforms should be expected with a lower HFF setting?

When the high-frequency filter (HFF) setting is lowered in polysomnographic monitoring, the resulting waveforms become rounder. A lower HFF setting allows more lower frequency activity to be displayed on the recording, smoothing out sharp edges and minimizing the appearance of faster transients in the waveform. This leads to a graphical representation of brain activity where the peaks and troughs of the signals are less pointed and more rounded.

Rounder waveforms indicate that the higher frequency components of the signal are being attenuated, which is often desirable in certain instances, such as when analyzing slow wave sleep or identifying specific patterns in the brain's electrical activity. This filtering can help clarify features of the sleep stages or disorders being evaluated. In contrast, other settings or filters would lead to different waveform shapes, which may not be as suitable for specific diagnostic purposes.