I'm not an audio hardware expert, so I need your help. I need a small device that will take audio input from a mic (using a standard mic jack), process / filter this audio and apply amplification and noise reduction as well as other possible other audio enhancements (if available), and output this to another jack where I can connect speakers or earphones.

Does anyone know of anything close to this. I know I could do this in software, but I need a small, highly portable device.

Thanks for any suggestions.

Yo,

Right up my alley!!!! Look at this thing...maybe just what you need! Enjoy the demo!!!!Ehrm...what do you need it for?

Thor

Thanks for the input. I think that will definitely do what I want, but it's quite a bit bigger and more complicated than I thought it would be. I was hoping for something maybe 1/4th or 1/6th of that size and bit simpler ... I mean I don't know what all those knobs are for.

I want to build a cheaper version of an electronic stethoscope with background noise reduction and maybe some amplification. I know that it may never work, but I cannot afford the pre-built ones that cost about $1000. I was just gonna hook up a disassembled mic to the head of the stethoscope, run the output through a hardware filter, and then to some headphones or speakers. It would be really cool if I could do it, because most of it is simple, except for the part mentioned in this thread ... which will probably prevent me from building it.

A good place to start would be with something like this-

http://rockgrotto.proboards.com/inde...nt&thread=3621

You probably wouldnt need noise filtering/reduction, as long as you have a decent mic. If you do need it, soemthing like this might help-

http://www.sanantoniohams.org/Tips/whine.htm

That is interesting, but it says it is designed for AC to DC rectifiers that are not working properly. Will it still work for other purposes ?

I suppose I can try it with just a mic.

Ok, after a good amount of searching I think I found what I might need:
http://gilmore2.chem.northwestern.ed.../noise_prj.htm

It looks complicated tho ... I hope I can build it. Does anyone know of a pre-built circuit like this ?

IMHO noise cancelling is a gimmick. A pair of headphones with good frequency response, and a good seal around your ears are way better.

Personally, I don't think you need any kind of noise reduction. A decent electret mic and a reasonable amp (all you'll need is a basic mic preamp, something like this http://cgi.ebay.co.uk/B-Tech-BT26-ph...item2a115b0eb0). If you find you really need any effects, they can be done in software I guess.

EDIT: http://www.jaycar.com.au/productView...t&form=KEYWORD

It's even got provision for an electret mic on the board.

I think you are right, I will get a mic preamp and see how it goes.

Hi,

A stethoscope, eh? Hmm, velleman is known to have some nifty kits...maybe this one would do...

(getting that medical degree after all?)

It looks cool, but where is the mic ? Don't tell me those clamps are the mics ...

Yes, I hope to get a degree at some time.

Well, it is a stethoscope in the strict sense of the word, but for machines, the clamps seem to be clamp-on microphones and there is an audio probe. I've seen a maint crew use something like that on one of the conveyors (at work) to pre-detect failures...and they used it in a pretty noisy environment, so the result should be passable...

Hmm, lemme sniff around ... okay, would something like this do? Just trying...because

...that means that "clamping" someone down, is (just maybe) not an option

Anyway, glad I could help in your carreer!!!

Thor

Thanks, that may be just what I need, except the mic is on the board. But, there might be a way to modify their build instructions to use an off-board mic.

You're welcome! I hope the kit is still available. As far as the mic is concerned, that does not HAVE to be on the board, some good (shielded?) wire may just do the trick.

Again, glad to have helped!

Wellness

Thor

I got a mic with preamp from a local store and it works quite well. It is already better than any stethoscope I have. However, the signal to noise ratio is not that good. Maybe I need a better mic.

stethoscope microphone
Some results about listening through walls ( ), others nearer to what you want.