A flanger creates a "whooshing" "jet plane" or "spaceship" sound, simulating a studio effect that was first produced by recording a track on two synchronized tapes and periodically slowing one tape by pressing the edge of its reel (the "flange"). When the two tapes' audio signals are later mixed, a comb filter effect can be heard. Flanger units add a variably delayed version of the audio signal to the original or signal, creating a comb filter or Doppler effect. Some famous uses of flanger effects include "Walking on the Moon" by The Police, the intro to "Ain't Talkin' 'Bout Love" by Van Halen, and "Barracuda" by Heart.