A high-frequency setting of 35 Hz would attenuate 50 Hz muscle activity by approximately what percentage?

In the context of EEG recording and filter settings, a high-frequency filter is designed to allow higher frequency signals to pass through while reducing the amplitude of lower frequency signals. When a high-frequency filter is set to 35 Hz, it will effectively attenuate signals above and below this frequency range, impacting muscle activity which often occurs in the 50 Hz range.

The correct answer indicates that with a high-frequency setting of 35 Hz, muscle activity at 50 Hz would be attenuated to approximately 40%. This is based on the principle that higher frequencies (like 50 Hz) will see a significant reduction in amplitude when passing through a filter that is set below their frequency. Specifically, a 50 Hz muscle activity would not be entirely cut off, but rather would be reduced in amplitude as the filter functions to suppress frequencies that exceed its cutoff point.

Thus, the filter attenuates the 50 Hz muscle activity by about 40%, reflecting the influence of the filter on the recorded EEG signal. The choice aligns with the understanding that the effects of high-frequency filtering are not uniform across all frequencies, and muscle activity, while diminished, may still contribute to the EEG output.