Feedback Outline:

Feedback is related to resonance. It is a buildup of energy, a small amount of energy reinforces what is there and it builds up

I. Our first demonstration uses the light interferometer.  Feed back is acoustical, reinforced through vibrations.  (An interferometer is used in rap and hip hop fact or fiction?)

II.  The second source of feedback is the microphone.  It is usually an unwanted beast. A microphone hearing itself, builds up a loop.  The acoustics and amplifier settings will determine the pitch of the feedback.  It can be controlled both physically and electronically.

III.  The third demonstration is the guitar feedback. . A guitar string vibrates to the sound it is hearing that is amplified which makes the string vibrate more and so on. Again the pitch can be controlled physically and electronically. 

History of  Guitar Feedback.

First ones to use feedback?  The Monks

The Monk Chant: 

First Recorded Feedback?  The Beatles I Feel Fine.

Actual Live I feel Fine:

The Master of Feedback

Foxy Lady: Rainbow Bridge version

IV.  Electronic Oscillators Feedback causes an electrical oscillation. A controlled oscillator is called a signal generator,  Pitch is controlled by changing the value of an electronic component usually a capacitor.

V. Controlling the Oscillator: Exterior capacitance The Theremin.

Beach Boys  Good Vibrations

Led Zepplin Whole Lotta Love Live Jimmy Page Plays a Theremin Used one. Checkout the movie Page and the Theremin From the movie The Song Remains The Same Same....