Sound file formats

The following sound formats are most commonly used in computers;

  • AIFF
    Audio Interchange File Format
    This sound format is supported by both Macintosh and Windows computers, so it's probably the best sound format to use.
  • WAV
    Most common sound format for PCs.
  • SND
    Most common sound format for Macintosh.

Bit depth and Sampling Rate

When an analog sound is digitized, the resulting sound file will contain a sequence of numbers that represent the level of the sound over time. These values are sometimes referred to as "samples" because the value of the sound is measured (or sampled) over time. Sounds are usually digitized at either 8-bit or 16-bit sounds. This refers to the number of bits used to store the "value" of the sound. With 8 bits, a computer can store 256 different values, so from the lowest to the highest point in the signal there are only 256 steps. With 16-bit sound there are 65,536 values from the lowest to the highest.A 16-bit sound file more accurately reproduces changes in the sound because different sounds will be stored as a different value in a 16 bit sound that would be stored as the same value in an 8-bit sound.

The frequancy of the samples (how often they are made) also effects the accuracy of the sound. Typically a sound is sampled at 11 kHz (kilohertz), 22 kHz or 44.1 kHz. Hertz means "per second," so 5 hertz would be five times a second, and 22 kilohertz is 22,000 samples per second.

CDs store sound at 16-bits, 44.1 kHz. DAT (Digital Audio Tape) will record at 48 kHz.

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