The Sweep Enable feature is unique to FREQUIA and allows you to choose whether to hear the equalizer parameters change in real-time as you adjust the controls. When disabled, the audio output will be muted every time you adjust a parameter (frequency, gain, or Q), then unmuted one second later. This prevents you from hearing the parameters change and forces you to estimate the answer based on your memory.
Sweep Enable only impacts the Response signal. You will only hear the effect of disabling Sweep Enable if you are monitoring the response signal.