Choosing the Right Bit Rate

Besides compressing the data in an audio file, all compressed file formats also let you choose the rate at which the original music is sampled. The lower the sampling rate, the smaller the file size; the higher the sampling rate, the better the sound quality. It's a trade-off.

For example, if you choose to encode an MP3 file at a 128Kbps bit rate, a three-minute song that takes up 32MB in uncompressed format will compress to just 3MB of storage. That's small enough to download easily, or to send via email.

Note Sound quality is highly subjective, as you can imagine-some "golden-eared" audiophiles find it difficult to listen to any audio files created with lossy compression- no matter what the bit rate.

Both Apple's iTunes software and Windows Media Player let you rip songs at a variety of bit rates, from 16Kbps to 320Kbps. Obviously, the lower bit rates are appropriate only for spoken word or low-fidelity recordings; the higher bit rates are more appropriate for higher-fidelity recordings.

The default bit rate in both iTunes and WMP is 128Kbps, which is a decent compromise between sound quality and file size. Know, however, that while some refer to this bit rate as "CD quality," it really isn't; the quality is more like that of a good FM radio station-which, as I said, is good enough for most listeners but not necessarily for audiophiles.