microphone s/n improvement
microphone s/n improvement
(OP)
Hello
I need to improve the sound collecting ability in a
location where there is little background sound energy.
Can I connect several microphones in parrallel to improve
the signal to noise ratio. In other words I want to use
several cheap microphones instead of one expensive one.
Thanks in advance for help
2dye4
I need to improve the sound collecting ability in a
location where there is little background sound energy.
Can I connect several microphones in parrallel to improve
the signal to noise ratio. In other words I want to use
several cheap microphones instead of one expensive one.
Thanks in advance for help
2dye4





RE: microphone s/n improvement
My feeling is that you will get the best improvement with a more sensitive microphone. You may also want one with a cardioid response pattern. Can you also mechanically filter the sound, I mean adding reflectors to improve the gain in the desired direction, or to diminish the unwanted sources, like these microphones with parabolic reflectors used in the football games to pick up the voice of the officials.
RE: microphone s/n improvement
sensitivity. I refer to noise as the electrical noise
generated by a microphone without sound present.
If several were paralleled this noise would cancel
but the sound signals are corellated and would add.
Is this possible ??
thanks
2dye4
RE: microphone s/n improvement
Bear in mind that you would need a minimum of 4 microphones to get a 6 dB improvement in signal to noise.
If your electronics is that noisy, I could get better electronics to start with. Particularly if you're talking about 2 or 4 times the number of microphones and amplifiers. You are almost always better off starting with a cleaner signal than to try an clean up a signal after the fact. You could easily get sufficient phase error in the positioning and equipment to mess up whatever you're trying to measure.
As a final note, a decent configuration and electronics allows the Army's BAT submunition to detect tank acoustic signals from kilometers away.
TTFN
RE: microphone s/n improvement
RE: microphone s/n improvement
Some clarification.
What i would like to do is use cheap pc mount microphones
that cost around $.60 each. They are physically small
enough to mount ten of them together on a pc board in
a 2" by 2" square. With this close proximity the sound
recieved should be in phase. Each microphone feeds through
a resistor to the inverting input of a operational
amplifier configured as a summing amp. So ten mics and
resistors and 1 low noise op-amp. I think the electrical
noise from each mic will be gausian and uncorrelated with
each other while the input sound signals will be
correlated. The noise will add by factor of sqr(2).
My goal is get the sensitivity up much closer to the
human ear.
Does the noise in this case add by (sqr(2))^10 or is this
equation not correct.
Thanks
2dye4
RE: microphone s/n improvement
Additionally, you've created a bigger antenna for picking up stray noise and a bigger collecting aperture for picking up ambient noise.
TTFN
RE: microphone s/n improvement
Write a computer model !
<nbucska@pcperipherals.com>
RE: microphone s/n improvement
RE: microphone s/n improvement
IRstuff and felixc have some valid reasons why what you suggest is a bad idea. If you start with a good quality microphone, connectors, cable and electronics, you are better off than trying to clean up the signal.
You have said that you want to achieve the sensitivity of the human ear with an array of really cheap microphones and you assume that the noise from said microphones is electrical rather than acoustic. How about some more details:
Is this to be used indoors or outdoors? Would a windscreen help?
Is the source fixed in relation to the microphone (in direction if not in distance)? Can a directional mic be used? If the direction isn't fixed, can a directional microphone be rotated toward the source?
What frequency range do you need to cover? At some frequencies and some microphone spacings the signal will cancel!
RE: microphone s/n improvement
This will be indoor use.
I understand a reflector for sound has to be some
significant portion of a wavelength for the lowest
frequency of interest. If this is true it makes the
dimension too large.
All electronics are on the same pc board and a
high quality low noise op-amp will be used for the
summing and preamp.
thanks
RE: microphone s/n improvement
TTFN
RE: microphone s/n improvement
If your time is money, it is a loosing proposition.
<nbucska@pcperipherals.com>