The sound recording

• Making a sound recording with a tape recorder.
  Cornell Lab of Ornithology has a web page that describes the equipment used to record bird sounds. All the equipment described is top of the line and very expensive by my standards.
  All my recording equipment together cost me about one hundred dollars. Of course I am not in the business of making archival recordings. My main purpose is to record with enough fidelity that a sonogram of the recording will allow me to identify the bird.
  If you buy a tape recorder, make sure it has an external microphone input. Other desirable features include a tape counter, and an external pause control input. This should set you back about fifty dollars. When you are ready for more professional recordings then get ready to pay ten times that much.
• I have recently acquired a camcorder and am in the process of evaluating its use for recording bird songs by attaching my parabolic microphone to its mic. input. Initial impressions are that it has better fidelity than my audiocassette recorder, can record longer intervals without changing tapes, automatically dates and times recordings, and it has the added advantage of recording behavior.
• My microphone is made with an 18 inch parabolic reflector, purchased from Edmund Scientific's (stock#T80,254) for $36.50, a Radio Shack microphone element (stock#270-092 $2.99), and ¾ inch pipe fittings($5.00).
• (I have included page with a diagram of the microphone I use to record sounds. It is very simple, cheap, but it works.)
• Obtaining pre-recorded material (audio tape or CD)
  I do this when I want to compare my recording with professional ones. This is helpful in making an identification of an unknown bird. Most sound boards come with utilities that will allow you to connect directly with the CDROM drive of the computer, or with a line input for an external tape player.
• Recording directly to your sound card.
  I use the SoundBlaster sound card for my PC computers. The Macintosh has sound hardware built into the computer. All you need is a compatible microphone and a long enough mike cord to go to the source of the sound. This seems to be a great job for a super laptop.

Digitizing the sound file

Once the recording is in hand, it is played into the line or microphone input of your sound card. I find it useful to send the output of the tape player into a graphic equalizer and then into the computers sound board. This allows me to filter out some of the low frequency noise (dogs barking , traffic etc.). Here is a diagram of how my computer is set up for sound recording and playback.

Using a sound digitizing program, such as SNDREC32.EXE (which comes with Windows95) or CoolEdit , create the sound file in 8 or 16 bit monaural format, (e.g.WAV format if you are using Windows) at a sample rate of at least 11,000 samples per second, but preferably at 22,000 or 44,000 samples per second. The sampling rates that you can use depends on the sound card that you have. The size of the sound file is proportional to the sampling rate..

The larger the sampling rate the higher the frequency that can be analyzed by a sonogram program.

The relation is very obvious. If you are going to digitize birdsongs, which have frequencies up to 10,000 Hz, you should at least use a sampling rate of 20,000 Hz.

When you download sound files from the Internet , check to see what sampling rate is used. It is not unusual to see many digitized at 8,000 Hz, which makes them useless for sonogram analysis , unless they are recordings of owls, doves or crows etc.

I have a SoundBlaster 2.0 sound card on my older computer, and I use the DOS program BlasterMaster (available on Compuserve) because it allows me to use the cards highest available sampling rate of 15,000 samples/sec. I then use Gram23 to produce the sonograms.

On my newer machine I have a SoundBlaster 16, which allows me to record at a sampling rate of 44,000 samples per second and I use CoolEdit to digitize the sound and Gram23 to create the sonogram. I have also used the program Sona available as freeware at Avisoft. It is more sophisticated but harder to use.

If you have a Macintosh computer, Cornell Lab of Ornithology sells the Canary program that is a powerful but expensive sound analysis program

Windows 3.1,which I have installed on my older computer, has its own sound recording utility, which on my computer can only record at 12,000 samples/second. Windows 95 has a much better recording utility which can record up to 44,000 samples per second. Search around the Compuserve forums, read the manual for the sound card, and use whichever program that suits you.

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