I don't know if this is the same thing we are talking about but here goes/. Eric Clapton was famous for his use of WahWah pedals when he played with Cream. My under standing is a wah wah runs the tone of a given note or chord from extreme treble through the midrange and back again as you raise and lower the pedal while the note remains the same the wah is changing only the tone. The note or the pitch is the constant vibration of a string, the tone is color of the sound, warm or brittle as the case may be.

Don