All this month I'll be looking at some of the more popular audio signal processing effects out there, which I'm sure you'll recognize from some of the most successful songs ever recorded. Impress your friends next time one of these babies comes on the radio by saying, "Wait, check out this part and listen to the ____!"

If you missed last week's post on flangers and phasers that can be found here. Today, let's fill in that blank with the wah-wah effect, which you could think of as a device that tries to imitate a human voice saying the word wah. The first, original wah-wah, and still the most popular version, comes in a foot pedal that allows the musician, generally a guitarist or sometimes keyboardist, to vary the peak response frequency of a small filter with his or her foot. By rocking back and forth on the pedal, as you'll see in the video below, you can create all kinds of different wah effects.

Beyond the more famous examples, like Jimi Hendrix's "Voodoo Child (Slight Return)," I've always loved the wah-wah effect as it was used in 70s-era disco tunes as a punchy "chicken-scratch" on the rhythmic guitar tracks. Listen to the waca-waca guitars in these two classics:

"Night Fever" by the Bee Gees

"Charlie's Angels (TV Theme)" by Henry Mancini


What are some of your favorite songs that show off the wah-wah pedal?

Check out past On Music posts here >>