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Is there an understandable explanation of feedback for normal people?
Plug a microphone into the AUX jack on your stereo, and then hold the mike in front of a speaker that screech you hear is audio feedback.
If you hit a bell it makes a ringing tone. Any given bell always makes the same tone the principle of church bells. If you set a sound system to output that same tone, the bell will start to ring in sympathy also feedback. But in music, we say that the bell resonates, but it is the same thing.
All systems from a simple bell to a complex sound system have at least one resonant frequency where the note continues at the same frequency for as long as energy is supplied positive feedback. Bad sound systems (and bells) have more than one resonant frequency.
Non-resonant frequencies die away much faster than resonant frequencies, so much more energy is required to maintain that particular sound. That is negative feedback.
Finally, if you hit a bloke down the pub, he will probably hit you back feedback, but not as we know it
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If you (CO2) punch a professional boxer (H2O) in the face, hell knock you coldern a mackerel. Instant negative feedback.
If a bully (government funder) punches a coward (grant-seeking academic climate scientist) in the mouth, hell cry and beg for mercy (promise to prove CO2 rulez). This excites the bully who will proceed to pound the coward into a pulp (utterly destroy his integrity). Run-away positive feedback.