Hey Schelo - well, thru-wall recording is usually the trickiest and most expensive part of our hobby I'm afraid. If this is gonna be a one-off, I'd feel wrong telling you about any expensive gear for the job.
This is worth bearing in mind though. Your ears are pretty good compared to most mics. Spend some time figuring out the best place to listen from when you know she's in next door. Doors are usually a weak point because there's space underneath them for sound to escape, failing that you want to be close to a window or a fake deviding wall. If you can hear her TV or music or her talking on the phone or something, you know you've found a good spot and you're in business. My point is that if your ears can hear it, then almost any gear will pick it up.
So, if you can find a good place to listen from, first of all check your mp3 player if you own one. Many of those can record, and in the right place they'll do a good enough job. If you own a video camera or a digi cam that does video, many of them have ok sound quality too. If you don't own an mp3 player yet, Iriver T30 and Creative Zen Nano come highly recommended and fairly cheap.
Hopefully some of that helps. Keep us posted on how its goin, and the very best of luck with your mission!!
I've heard that their are devices designed for musicians that will pick up vibrations on accoustic guitars that could be used for that. Just something I came across once. Haven't tried it. I wonder if there is a musician or "hobbiest" out there who might be familiary with what this device is called and how well it works.
Hey Rograd - You're talking about Piezo pickups. Good thinking in theory, except the floor in the plan is that for the most part piezos wouldn't be up to the job. They sound good enough for live use and they're worth having over a condenser mic because you can pump one up way more without feedback, but for a decent active system you're looking at way too much money for this job, and even then every piezo I've heard in isolation still sounds pretty course. Most acoustics I've played with a piezo fitted tend to miss out a lot of the finer points of what you're playing, and thats with the amount of vibrations an acoustic puts out, shoudln't think it'd even register through a wall. As far as I know there are mics being manufactured that work along similar principals, probably with way better response for a situation like this... but again you'd be talking serious money.
Thanks for the reply Scott... Too bad about those guitar units. I read about them, but haven't given it a shot yet.
Just for fun, I did some checking online to find the lowest price I could find for a mic system that states it's designed for through wall pickup. The lowest I could find was $145 U.S.
This is a super sensitive transmitter using a piezo diaphragm in place of a microphone allowing it to pick up audio through glass and thin walls. The unit's tuned transmission frequency is between 86 - 96 MHz on the FM band. It is quite stable allowing for strategic positioning inside or outside of a room for monitoring. It has a 160 cm wire antenna and will transmit up to 400 metres, requiring 2 x 'AA' batteries, lasting 250 hours of use.
I have seen mics similar to the one you found for listening through walls, except it was around $200-250 but not 'wireless'. From my experience with wireless gear (video and audio), you would get a much cleaner recording if you went the hard-wired route. Wireless always picks up transmissions that will make your recording unclear (even lights, tv, etc)... there is just too much interference in a hotel/home setting to get a good recording with them.
The 'through-wall' rigs I have seen are advertised as being used for plumbers and electricians to find spots in the walls. I have thought about getting one... but could not justify $200-250 for a new gadget in my collection. One other thing to think about would be background noise/interference. The location I wanted to try this gadget on had good acoustics in the walls... but excessively noisy pipes/wiring (you could hear it buzzing), plus was near the freeway (if you put your ear to the wall, you could hear the people in the next room, but also the cars going by). I did try baffling an electet mic and tried using a shotgun mic to get the sounds, but neither had good results in getting sounds from the next room.
Just some things to think about. Good luck with your venture... keep us update with which equipment works!
) so I hope you don't mind me asking a question in my first post: