Trivia
Feedback: Great for guitar playing! Not so great for karaoke...

Have you ever been at karaoke and someone raised the microphone volume too high? You probably heard a very unpleasant noise indeed. This is called feedback. It is an endless loop of noise caused by the microphone picking up the sound from the speaker, which is then output from the speaker, again picked up by the microphone, and so on. Although this sounds awful in karaoke, it can be used to nice effect when playing rock guitar. The pickups found on electric guitars take the vibrations of the strings and output them as sound to an amplifier, which then plays the sound from a speaker. Sound output from a speaker is actually just vibrations in the air. If the speaker and guitar are too close together the sound will grow too loud, and the vibrations in the air will cause the strings to vibrate, which is then again picked up by the microphone, creating an infinite loop. This is similar to the feedback effect that can occur with a karaoke microphone, but with an electric guitar this has the effect of endlessly "elongating" the sound from the strings. This is referred to as "feedback playing." For the first guitarists who experienced feedback this phenomenon was certainly a nuisance. However, some guitarists realized that they could control this effect to a certain degree, and began using it as a playing technique. Note that the position of the guitar relative to the speaker has an effect on the sound: the tone is higher in front of the speaker and lower to the side. This is one reason why guitarists on stage stand and point their instruments in different positions. Who would ever imagine that the feedback that annoys us all in karaoke could be deliberately used in playing the guitar? The world of rock and roll is certainly an interesting one!

Feedback: Great for guitar playing! Not so great for karaoke...