Apple 8 manual Digital and Analog Recording

Digital and Analog Recording

While digital audio recording is similar in concept to analog recordings made on tape, the technical differences are significant. For much of the 20th century, and into the 21st, analog tape recordings have been used for the storage of audio performances— spoken, sung, and played.

The analog tape medium is a thin plastic strip coated in tiny metal particles. It is usually stored on a roll or spool, or as a cassette tape.

The process of analog tape recording involves the transmission of small electrical charges, sent to the magnetic heads of a tape recorder. Changes to the strength of these charges alter the magnetic fields generated by the heads, and rearrange the positions of the metal particles on the tape. Needless to say, this is a less than precise science. Due to the randomness involved in the rearrangement of magnetic particles on tape (and other technical reasons), the recordings are said to be analogous—similar to the actual performance.

Digital recording, on the other hand, is much less random. Analog signals are converted into digital audio signals via the ADC (Analog to Digital Converter) of the audio interface. The digital audio signal is stored on your computer hard disk—as a series of ones and zeroes—in a digital audio file. Provided this file remains uncorrupted (and is not edited or altered), the digital recording will be identical each time it is played back.

In a copying situation—tape to tape—there is no comparison between analog and digital recordings. Each subsequent copy of an analog recording becomes noisier, and less like the source material. This is the random factor of the magnetic particles becoming less like the original each time a copy is made.

Digital audio files, on the other hand, can be copied any number of times, with each subsequent copy adding no noise. It is simply a file copy.

On a more practical level, digital audio files stored on hard disk have the following advantages over analog audio stored on tape.

ÂDigital audio can be cut, copied, and pasted freely from location to location. Could you imagine physically cutting a stereo analog recording stored on tape into even four or five segments, and splicing them back together? Not much fun!

ÂYou can move to any spot in a digital audio file almost instantly, rather than waiting for the tedious mechanical rewinding and fast forwarding of an analog tape machine.

ÂYou can process digital audio in ways that are simply impossible with analog audio. As one example, it is possible to adjust the pitch of a digital audio file without changing its speed.

Appendix A Audio and MIDI Basics

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