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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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