Instead of the effect being controlled by a pedal, as on a standard wah-wah, the effect alters in response to the volume of the input signal. Like a wah, it works by adjusting a peaking filter, which amplifies a specific frequency and cuts off other selected frequencies. Since the electronic circuits in the effect can respond much faster than a human musician can physically move a pedal, certain effects that a standard wah cannot achieve are only possible with auto-wah. The response of the effect is highly interactive with the dynamics of the input signal - this makes it possible to vary the response at will via slight adjustments to playing technique. Therefore it may take some practice before the response of the auto-wah can be wilfully controlled in order to achieve a consistent sound.