[WebSerf]

I want to use a baby monitor to make a remote audio connection to my computer for voice input and I want to disconnect the speaker on the baby monitor that is next to the computer and wire directly into the microphone input. My intention is to eliminate the acoustic link and get the best possible sound quality into the computer for the most accurate speech recognition.
I tried, in my ignorance, to directly wire the speaker leads (8 ohm speaker) directly into the microphone jack on my soundblaster live 5.1 card. As you probably have guessed, I no longer have a functioning microphone input to my card
I've heard the term "impedance matching" but I really don't know how to go about it. The sound card mic input, according to the Creative Labs website, has an input impedance of about 5,000 ohms.
Anybody have any help or advice for this audio incompetent?
Thanks.

[booga007]

Without doing a search I cant figure out the electronics side of it... but it'd be best to try and find the output before the amplification stage that feeds the speaker on the monitor... that way you're getting a line or preamp'd signal and shouldn't be too much of an issue to feed it to a pc.

[WebSerf]

Thanks for your input. We are going to try a matching transformer (8 ohm to 1 Kohm) and a 5 Kohm pot in series on the mic side. I expect we'll have some noise issues and we'll have to figure/filter that out as we go. I agree that the preamp output would be a less risky signal level to put into th PC but, I think, impedance matching would still be an issue and we're not confident that we can find the right place on the circuit board to connect or, if we can ID the spot, make the connection without damaging the components. Maybe someone else will have another, better method to try and will point me to an "ideal" (read: cheap and effective) solution. I was an electronics tech 35 years ago in the USAF but those skills are REALLY rusty!
Otherwise I'm in for (arrgghh!) learning!

[guitar]

Originally Posted by WebSerf

get the best possible sound quality into the computer for the most accurate speech recognition.

the mic in a baby monitor is crap you'll never get a good sound quality with it
a plate mic from tandys will do a better job for cheap or buy a shure plate mic {expensive}

[WebSerf]

Thanks for your help.
Unfortunately there is no mic jack on the baby monitor. We're already hacking into the local (at the PC) monitor to wire in an impedance matching transformer and to wire a better quality mic to the other one is an additional challenge that, if possible, we would like to avoid.
I'd like to use a mic locally but the wireless link is pretty important to the setup we're doing. We want to be able to give voice instructions to a program running on a PC from a remote location anywhere within the wireless range of the baby monitor. We already know it will work, with some unreliability, using an acoustic coupling between the monitor speaker located close to the PC and picking up the sound with a mic plugged into the sound card. It is not out of the question that we may, eventually, build (or find someone to build) from scratch a system similar to the baby monitor but with better audio properties but, for now, the baby monitor is the best wireless link we've found. This is only one of several (many? ) technical challenges we will need to overcome but we'll keep trying.