Flange is an electronic delay effect created by combining an audio signal with a version of itself that has a varying delay (of around 15 ms), called a variable comb filter.

 

Flange is also a hollow, swishing sound created using the flanging effect.

 

Flange was originally achieved by running two identical analog reel-to-reel tapes; one was de-synchronized by applying slight pressure to the flange of the tape reel.