About the Recordings

Listening and Downloading

Click on the Listen link with the left mouse button to listen to a recording. This should start software on your computer that is used for listening to streamed audio.

Click on the Download link with the right mouse button (Windows) or Command Click (Apple). Your computer should ask what you want to do with the file. Choose "Save file" (or something similar) to download the file to your computer.

Recording Format for Dialup Connections

The audio files are in MP3 format at a 32kbit/sec rate. This is done so that dialup users (typically 48kbit/sec) can listen to the recordings without an extensive delay. If downloading files using dialup, it should take about the same amount of time to download the file as it takes to listen to it. While this low bit rate does not give the best audio quality, it does give a sense of what the performance was like. The original recordings use standard CD quality 44.1kHz, 16bit format. The CDs that are available at the Cortland Library are made using the original full quality recording.

Recording Method

I prefer to record events rather than make recordings. Simpler is better.

I use a pair of MX990 condenser microphones that are spaced a little less than a foot apart, with the active faces of the microphones are turned at 45degrees from the direction of the sound source. The left microphone turned to the left, the right microphone to the right. This is not the method described in the couple of books on recording that I've thumbed through; but I settled on this as the most realistic stereo configuration. See the sketch at the bottom of the page.

An Alesis 8 mixer provides the phantom power for the microphones and has a digital stereo output via a USB connector.

The digital stereo goes to a laptop that is running a program called Audacity, a great, open source, free download program. I'm using Windows XP, but Audacity will run on Windows, Mac or Linux. It can be obtained at SourceForge (I'll put in a link when I get a chance).

At the moment (April 2007) I have not used any amplitude compression on the files. I probably should.

Comments are welcome. Use the "Contact Us" form (use the button at left).

-John Sikora

Stereo Microphone Configuration

Below is a diagram of an experiment with microphone orientation using several metronomes in a room. The microphones were oriented at 45 degrees as show. The spacing between the microphones was varied while listening to their signal with a set of stereo headphones. With a spacing of about a foot, the sound seemed to be coming from the actual sources. With a wider or narrower spacing between the microphones, the sources either sounded closer together or further apart than they actually were (I don't remember which was which, this was done several months ago). My guess is that the human ear uses the phase differences between the left and right microphones (in addition to the amplitude differences) to determine object positioning. This is probably a well known fact, but I do not have any references.

Stereo Microphone Pair and Three Metronomes (top view)