Digital Audio Recorders - Better than tape? Yes, but...
While we're in the "digital mythbusting mode" allow us a moment to tackle digital AUDIO recorders.
Ah, yes, the march of progress. Remember the video rant? Yep, same thing here.
If you're relying on the new state of the art digital audio recorders to record important statements to be possibly used in a trial presentation here are a few tips that will make your life a little easier and your presentation a little smoother:
Unless you’re going at full CD quality, your digital recorder is tossing stuff out to save space. Supposedly your ears will not miss the missing stuff, but our forensic audio equipment sure will. You want your machine to toss out as little as possible, and that means running at the highest "bit rate" you possibly can.
To put it another way, if you are maximizing your recording time, then you are also minimizing your recording quality, and also the amount of help we can be to you. If you need to record for a very long time and have to go to a low bit rate to do it, then it’s time to invest in new equipment with more storage space. As with video, it’s better to get a small amount of useable material than a large amount of junk.
A lot of these portable digital recorders have
bit rate settings that are so low that it’s crazy. We recently received a recording made at such a low rate that the recorder literally threw out the background conversation it was supposed to be capturing, concentrating all its efforts on the louder crying baby it was also picking up. We were still able to improve things a little, but not much.
Ideally you should be recording in either AIFF (Audio Interchange File Format) or uncompressed WMA (Windows Media Audio) format, 44.1 kHz sampling rate or better. (Better is overkill unless you’re recording concerts or something.)
What about stereo vs. mono? Well, for us, stereo is a lot more versatile. If you have a stereo device with a stereo microphone or microphones, then it’s worth it. However, stereo takes up twice as much space (IE double the bitrate) to get equal quality. If you are using a single microphone and it isn’t stereo, then there’s no sense in recording in stereo format – you’ll just be wasting space with redundant data. Also, we prefer a single channel of good mono to two channels of not-so-good stereo, so don't be afraid to use your own ears and your own judgment. Test, test, test!
Coming up next: "A FEW RANDOM TECH NOTES" - the kind of stuff you can quote when you're mingling with a new client and hit an akward moment of silence. Guaranteed to dazzle and amuse!
