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" .
EtymologyThe word is derived from the sound of the effect itself; an imitative or onomatopoeia word. The effect's "wa-wa" sound was noted by jazz player Barney Bigard when he heard Tricky Sam Nanton use the effect on his trombone in the early 1920s .
AcousticThe wah-wah effect is believed to have originated in the 1920s, with brass instrument players finding they could produce an expressive crying tone by moving a mute, or plunger, in and out of the instrument's bell . In 1921, trumpet player Johnny Dunn's use of this style inspired Tricky Sam Nanton to use the mute with the trombone .
By the early 1960s, the sound of the acoustic technique had been emulated with electronic circuitry (; ). For electric guitar the wah-wah pedal was invented.
TechniqueThe 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, or pedal. Often it is controlled by movement of the player's foot on a rocking pedal connected to a potentiometer. An alternative to players directly controlling the amount of effect is an 'auto-wah'. These devices, usually make harder hit notes more trembly with a more prominent wah wah effect . Wah-wah effects are often used for soloing or for creating a "wacka-wacka" funk rhythm on guitar . Although these electronic means are most often on electric guitar, they are also often used on electric piano .
TheoryThe wah-wah effect is produced by periodically bringing in and out of play treble frequencies while a note is sustained. Therefore, the effect is a type of spectral glide, a "modification of the vowel quality of a tone" .
The Electronic wah-wah effects are produced by controlling tone filters with a pedal . An envelope follower circuit is used in the 'auto-wah'.. Subtractive synthesis can produce a similar effect.