Here's another one for the list:
Many people have at some point in their life, experienced "ACOUSTICAL
FEEDBACK" - a loud piercing "squeal" or "shrilling" combination of sound
tones from Public Address (PA) system loudspeakers.
This condition frequently resulted from a combination of three devices
being interconnected:
a) Microphone (input device)
b) Audio Amplifier (booster)
c) Loudspeaker(s) (output device)
Furthermore, this condition is triggered by "POSITIVE FEEDBACK". This
means that sound waves radiating from the speaker, made their way
back to the microphone (through the air) "IN PHASE" and, the strength
(amplitude), exceeds a "threshold" trigger point.
Since the amplifier's job is to amplify (boost) sounds picked up by the
microphone, and then send them to the speaker (output device), this made
a "CLOSED LOOP" process.
This Feedback condition is usually created when:
a) the amplifier volume is turned up too high (Higher Gain),
b) the microphone is "Too Close" to the speaker,
c) something changed the "environment" between speaker and microphone.
ie: air humidity, etc.
Many other things will augment or reduce the "threshold" trigger point
level, such as "room acoustics", room resonance, certain sounds created
in the room, etc.
NOW, the reason I bring this subject forward, is because most people
don't evaluate or consider reasons for "specific" or "common"
frequencies that are associated with this "Feedback" scenario!
Also, even if the amplifier, speaker system, and microphone ALL HAVE
very wide, reasonably "flat frequency responses", or the devices are
"OUT DOORS", these frequencies are all in the SAME ranges! Same thing
occurs with a pair of two way radios, where one is transmitting and
the other is receiving with it's volume up high and in close proximity
to the transmitter.
I found some frequencies that seem to "Stand Out" more than others when
using a 3 band equalizer. They are: 125Hz, 247HZ, 1140HZ, 2270, 2650HZ.
Is it possible that the Aether has a range of "Ringing" frequencies?
I'm interested in hearing about other individuals findings.
I'll await their comments and "Feedback". <g>
<Dave>