In a flanger process, one path has no delay, the signal is fed to the mixing stage unchanged. The second method has a delay with which the signal is periodically varied, but only in a small delay range between 1 ms and 20 ms. This periodic delay is generated with a Low Frequency Oscillator( LFO).
Both signals, the undelayed and the delayed one, are mixed again in the mixing stage. Due to the delay of one signal, a comb filter effect with interference is created, resulting in a flowing audio effect where some frequencies are attenuated and others are amplified. The flanger circuit also has a feedback loop that can be used to vary the strength of the flanger effect.