Say “oooh” as in “noodle.” Then say “aaah” as in “park.” When you say “oooh” your mouth is more closed, with less resonating space and a smaller opening. This configuration blocks the higher overtones of your voice. When you say “aaah” your jaw and lips open, creating more resonating space and letting more high overtones through. Now glide from one to the other. The resulting “ooohaaaah” is the sound the wah-wah pedal is named for. By selectively filtering an electronic instrument’s overtones, the pedal can make it sound more vocal. It’s only two vowel sounds out of the dozens your mouth is capable of producing, but it’s a start toward making a more human tone.
Here’s a documentary about the wah:
Cry Baby: The Pedal That Rocks The World from Joey Tosi on Vimeo.
Combined with a guitar, the wah can do more than vowel glides. When you mute the strings and strum through a wah, you get a percussive sound ranging from “chicka chicka” to “chucka chucka.” By filtering the overtones differently, you can make other vocal sounds too. I have a digital effects unit that can make the guitar say the word “yeah” pretty convincingly. These kinds of effects give a guitarist the emotional immediacy of the voice combined with the guitar’s wide range of pitches and richness of harmonic possibility.
The guitar isn’t the only instrument you can use with a wah, and it wasn’t the first. The pedal was invented somewhat by accident when the Thomas Organ Company was developing a tone modifier for amplifiers. The first instrument they tried with it was an amplified saxophone, and the company thought they might market it for wind instruments in big bands, as an electronic version of the Harmon mute. A guitarist who worked for the company named Del Casher heard the possibilities of the new tone modifier, and he was the first person to make a recording of it in 1966.
Frank Zappa was an early adopter, and he introduced it to Jimi Hendrix, who would be the first to break it into mass consciousness with “Voodoo Child (Slight Return).” Jimi also introduced the percussive “chicka chicka” on “Little Miss Lover.” Jimi’s solos on “All Along The Watchtower” is another distinctive early adventure with wah. Plenty of other hippie rockers followed suit. George Harrison has a song called “Wah-Wah” on All Things Must Pass, named both for the pedal and for the Beatles’ whining during their final sessions together. Eric Clapton uses wah with Cream on “Tales of Brave Ulysses” and “White Room”.
Pop culturally, wah is most associated with seventies funk and soul, like on “Theme From Shaft” by Isaac Hayes, with Charles Pitts on guitar. Curtis Mayfield also had a distinctive and much-imitated wah style. From blaxploitation soundtracks it was a short jump to the porn movies that imitated them, which is why funky wah guitar is an effective comedy shorthand for getting busy. But wah doesn’t have to be seductive. Eddie Hazel of Funkadelic used it for a dark, spacey cry on “Maggot Brain.” Click here to listen to some standard wah techniques on electric guitar. The wah pedal sounds especially good on E9, the mother of all funk chords.
Hard rock and metal guitarists have found a vocabulary for wah drawing more on Hendrix and Zappa than on funk. Zappa used it less like a speech effect and more like a simple adjustable filter. He would leave it partially open to filter the high frequencies over the course of an entire song. Distortion exaggerates out the guitar’s upper harmonics and other partials, and the wah makes a great envelope controller. Jimmy Page used it on Led Zeppelin’s “Dazed and Confused,” “Whole Lotta Love,” “No Quarter” and “Custard Pie”. Slash used it with Guns N’ Roses, and Kirk Hammett leans heavily on it with Metallica.
Bassists sometimes use the wah too, especially in the funk and soul world. Michael Henderson played with one on Miles Davis’s album On the Corner. Other wah-loving bassists include Metallica’s Cliff Burton and Black Sabbath’s Geezer Butler.
Electric pianos and harpsichords operate in very much the same way as electric guitars, so it was only a matter of time before keyboard players started investigating guitar effects. Clavinet with wah sounds so much like guitar that it’s hard to tell them apart. Garth Hudson plays some pretty groovy clav with The Band on “Up On Cripple Creek”, but nothing is as funky as Stevie Wonder on “Superstition,” “Higher Ground” and his other seventies classics. Electric piano also sounds great through wah, again because of its guitar-like tone when played through an amp with distortion. Richard Wright uses it on Pink Floyd’s “Money”, and it’s on tons of Miles Davis electric recordings, especially the ones with Keith Jarrett and Chick Corea.
Any instrument that’s amplified can be played through a wah. Miles Davis got a devastating trumpet tone with wah on Live-Evil and his other darker funk records. A few saxophone players have experimented with it too, as the pedal’s original inventors intended. David Sanborn played with one on the David Bowie album Young Americans, and Dana Colley used it with Morphine.
Violin sounds great with wah. The leading practitioners are Jean-Luc Ponty in the Mahavishnu Orchestra and Boyd Tinsley in the Dave Matthews Band. Pink Floyd even tried some wah on an acoustic piano in their song “Echoes”, which also includes wah guitar made to sound like crying birds. I myself have found that wah sounds terrific on mandolin. I’ve also tried it on harmonica, but there it’s redundant since you can do the wah effect so easily with your mouth.
Wah is just one flavor of the envelope filtering you can do with a synthesizer. A lot of the craft of electronic music comes down to creative rhythmic use of the filter. A standard technique is to get a repetitive loop happening and then sloooowwwly open and close the filter over the course of a phrase or section. Since a sequencer or computer can play the actual synthesizer notes, it frees up the musician’s hands for complex multi-parameter filter control using knobs or touchscreens. We’re only at the beginning of our collective exploration of the artificial vowel glide in music.