The effect is called "flange" because before the advent of flanger pedals, sound engineers and musicians would press the inside of the thumb (the "flange") onto the tape reel to slow it down and speed it up to achieve the desired effect.
and shifts it from Treble to Bass to Treble continusly - depending on how much or how long you play-. What the 'Wah' does is that it changes the Bass to Treble -or vice versa, depending where your at- on the press of a pedal, and the flanger takes a little time.
There is slow and fast Flanger, but the Flanger cannot make the ' Wah' sound. With Tremolo, these two effects combinded will rock.
Songs that have Flanger: Blink-182- Obvious - the verse-, Asthenia -when the guitars some in, verse-, Here's you letter -intro-, Feeling This - intro, even percussion have flanger-. Simple Plan- I'd do anything - approx at 2:01, they have both Flanger and Tremolo-
I won't be there - intro-. Black Eyed Peas- Where is the love?
To listen on the ' Wah' listen to the solo in 'Cold' by Crossfade -the electric guitar version-
Flanger-Similar to Wah, or just change the Treble and Bass