Wah-wah (or wa-wa) is an imitative word (or onomatopoeia) for the sound of altering the resonance of musical notes to extend expressiveness, sounding much like a human voice saying the syllable wah. The wah-wah effect is a spectral glide, a "modification of the vowel quality of a tone" (Erickson 1975, p. 72), also known as a band pass filter.
The wah-wah effect is produced by periodically bringing in and out of play treble frequencies while a note is sustained. The word is derived from the sound of the effect itself—in other words, it is onomatopoeic. The method of production varies from one type of instrument to another. On brass instruments, it is usually created by means of a mute, particularly with the harmon (also called a "wa-wa" mute) or plunger mute. Woodwind instruments may use "false fingerings" to produce the effect. Any electrified instrument may use an auxiliary signal-processing device, usually operated by a pedal. This electronic means is most often thought of in connection with the electric guitar, but is also often used with the electric piano (Kernfeld 2002).
Wah-wah in trumpet and trombone playing
This technique has been used in contemporary music. Karlheinz Stockhausen notates the use of the wah-wah mute in his Punkte (1952/1962) in terms of transitions between open to close using open and closed circles connected by a line (Erickson 1975, p. 73). Although the most common method of producing wah-wah on brass instruments is with a mute, some players have used electronic filtering, notably Miles Davis on trumpet (Kernfeld 2002).
Wah-wah in electronic music
- Anon. (2007)." Wah Wah Pedal / Auto-Wah". FreeMusicSoftware.org (Accessed 12 June 2013).
- Erickson, Robert (1975). Sound Structure in Music. University of California Press. ISBN 0-520-02376-5.
- Kernfeld, Barry (2002). "Wa-wa [wah-wah]". The New Grove Dictionary of Jazz, second edition, edited by Barry Dean Kernfeld. New York: Grove. ISBN 1561592846; ISBN 033369189X.