What happens to waveforms when HFF settings are increased?

When high-frequency filter (HFF) settings are increased during a polysomnography or EEG study, the waveforms become sharper. Increasing the HFF reduces the amplitude of lower-frequency signals and enhances the visibility of rapid waveforms and higher-frequency activities. This results in a more defined appearance of the waveforms, improving the clarity of the higher frequency components while attenuating slower waves that might obscure important data. Therefore, clinical interpretation of the signals becomes more precise, allowing for a better assessment of sleep patterns or neurological activity. Enhancing the HFF essentially sharpens the visual representation of these rapid waves, making them more distinguishable for analysis.