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Why do i keep getting feedback from my speakers when i playback something i have

Last response: in Home Audio
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June 15, 2011 5:33:45 PM

I record myself singing using the internal mic in my laptop. But when I play it back, the sound is very quiet. If i turn my speaker volume up I just get high pitched feedback. I don't understand why? Any ideas?
Many thanks
Maria
June 16, 2011 3:15:39 AM

mazzie said:
I record myself singing using the internal mic in my laptop. But when I play it back, the sound is very quiet. If i turn my speaker volume up I just get high pitched feedback. I don't understand why? Any ideas?
Many thanks
Maria
How loud do you turn it up to? what kind of speaker is it also?
June 16, 2011 11:25:02 AM

sounds bizarre that the recording is producing a high pitched noise when played back.
it doesnt happen unless there is a problem with the amplifier driving the speakers (or the speakers themselves are knitted together in such a way that they bleed out a high frequency when pushed too hard)

a microphone will pick up the signal from the speakers if the speakers are not muted.. to say that the microphone records the speaker, the speaker plays back that recording, and the microphone grabs what the speaker plays again.. the chain of events go on and on until the high pitched squeel is heard.


to prevent it from happening.. you take the output that goes to the speaker, split it, then run a feedback sensor that doesnt allow the microphone to capture the speaker.
when the input detects the microphone is recording the speaker.. they seperate by using a filter that removes the speaker output.
so really, the speaker is recorded from the microphone.. and then the electricity picked up by the microphone shoves its way down into the mixer.. the mixer will then shove that electricity up to the microphone.

all in all.. the microphone diaphragm will be electrified to resist the speaker output.
anything that comes out of the speaker will be in opposite phase of what is being resisted on the microphone diaphragm.

but
that method is really old.
nowadays they do it inside the mixer, or with software.
simple phase opposite taken from a monitoring feedback 'feature' .
when the two opposite phases come into contact with eachother, they cancel out.. and it is like the speaker isnt there at all.

that is how you see comedians and musicians get up close to a speaker and the microphone doesnt make the squeeling noise.
there is a microphone feedback 'feature' in active use.

background noise suppressors are different.
they are a filter that removes anything that has some echo in the sound.
the echo is generally based on the signal to noise ratio of the input sound.
anything lower than the threshold is removed.
and if you had a speaker 50ft away that could play loud enough.. then that speaker would get recorded.

to say that the other method checks the audio for resonances, this is also true.
when you stand 15ft away from the microphone.. you can record the echo from the room.
that echo from the room walls is seen and thrown out.
the closer you get to the microphone, the less those echoes are.. even though you are still in the same room.
it is a principle of what is heard first and moving on.

so if your room has 2ms before the echoes start to sound.. the microphone would be programmed to capture only the first 2ms
it hardly works.
you program some software to do it once.. then program the software to repeat the function over and over again.. eventually you will see the program repeat itself so blistering fast that the echoes after 2ms are picked up IF there is LESS than a 2ms gap between repetitions.

maybe hard to do on a computer if the software is limited to ?ms function speed.
some things work in the nanoseconds category.. so if you start there, you might be locked out of going any slower.
and if you start somewhere higher, you might be locked out of going any faster.
but
when the hardware allows it, you just gotta make sure the repetitions arent any faster than your target number.

really..
this is bad, because you dont want 2ms chunks missing from the recording.
it doesnt sound as realistic as it could.
just like movies or video games playing at a faster frame per second.
when the frames per second are slow.. the void time inbetween each frame is higher, and that is what you see when the screen flickers.
with video.. it can give your eyeballs fatigue, and with audio, it can also give your ears fatigue.
!