First of all, thanks to Leafcutter John for encouraging me to look into binaural recording. As a result I spent most of last Sunday designing and building a set of binaural microphones. What’s surprising is that I had everything I needed in my home. I started with a couple of old Mac computer mics that my friend Kevin gave me a few weeks ago. I tore them apart and removed the electret capsules from the circuit boards. I found a set of silicone ear-buds from an old mobile phone headset that fit the capsules perfectly. After that it was pretty easy.
On my first attempt I used the cabling from an old set of airline headphones, but the stiff wire going from the right to the left microphone was too sensitive to vibrations. After all that work I decided to disassemble it and start again. This time I sacrificed an old pair of JVC headphones. The cabling was much better and had separate cables to each driver. This time I used a paper hole punch to modify the ear-buds so the back of the capsules weren’t stuck in a vacuum. I used colored heat shrink to specify left and right, added a tiny bit of foam between the capsule and the ear-bud, then mounted a couple of layers of foam over the outside.
I was pleasantly surprised by the few test recordings I made. For the majority of the tests I placed the ear-buds into my ears and kept as still as possible since the mics are quite sensitive while plugged into the Sony PCM-D50. I ended up using the 20dB pad, although I got a better sound without the low cutoff filter enabled. For some other examples visit this post on Leafcutter John’s blog.
Binaural Finger Snaps
I captured this very typical example of restaurant ambiance recently at my favorite neighborhood Thai place in Minneapolis. I’m still running the PCM-D50 through its paces, but I sense that I’ll be looking forward to a long and happy relationship. This one minute and seven second clip includes many of the usual sounds sounds of diners in a food establishment: talking, laughing, coughing, children, plates clinking, ice in drinks, footsteps of the servers, and take away being placed in paper bags.
One of the first few recordings I made with my Sony PCM-D50 was to capture traffic ambiance. This was really a pretty good test for the stereo imaging of the built in mics. I held the device, so there is some handling noise, although I did put a wind screen on the D50. This recording would have been impossible without it. The mics on the D50 are very sensitive to wind. Even indoors if an object, like a door, moves the air near the unprotected mics you will hear the capsules flapping in the breeze. Despite the wind screen you can hear a bit of wind noise around 00:34. The stereo image is acceptable, but it’s not as broad as other stereo mics I’ve used such as the Shure VP88. I have yet to try the 120 degree, Y pattern setting, which I imagine will spread the image considerably.
This is not a website about my cat. First of all, the cats are not mine. I just live with them. Secondly, I can get away with this because I’m posting an animal sound. Anyway, before I get myself in trouble by saying something regrettable about cats, my wife’s cat Minuit (French for midnight) has a really great purr. I managed to capture a little bit of it along with some cat swallows and a partial meow the other night when I first got my Sony PCM-D50. The photograph is not Minuit, but actually his chief rival, Caro, the newest edition to the family who embodies pure evil. Just look at those eyes!