A/D conversion |
the process whereby analog signal is converted to digital. The higher the
quality of A/D converters, the better the digital audio will sound. |
amplitude |
loudness of signal -- in the physics of audio, represents the maximum peak of an
audio wave. To the ear, amplitude is perceivable as volume. |
audio format |
describes how digital audio is written to a computer file. Different formats typically
have different headers, which describe possible bit depths, sampling rates, and the number of channels. Sound Designer II (.sd2) audio files can also
store region information, which is useful for digital mixing purposes. |
bit depth |
usually a multiple of 8; describes the number of bits which represent each byte
of audio data. A bigher bit depth means that more amplitude accuracy can be represented. |
CD audio |
the 16 bit, 44.1 khz audio standard (adopted c. 1979) |
compression |
means of reducing the amount of data used for a sound file. The main reasons
for compression were the lack of cheap storage for the audio, and the limited bandwidth for streaming audio on the Internet. mp3 and Real
Audio are the main compression formats in 1999. Compression is either lossy or non-lossy. With non-lossy compression, when you decompress
the sound it's the same as before the compression. Most standards, unfortunately, are lossy. |
D/A conversion |
the process whereby digital audio is converted to analog. Unlike in A/D conversion,
having 18-20 bit converters for 16 bit digital audio will make absolutely no difference in sound. |
DVD audio |
the 24 bit, 96khz. audio standard (adopted c. 1998) |
frequency |
how many times per second the sound occurs. To the ear, frequency is perceivable as pitch. |
hz. |
hertz: the measure of frequency in audio. In England, they measure this as cps (cycles per second) |
jitter |
the phenomena of digital distortion as caused by inaccurate sample rate clocks, generally when recording digital audio |
khz. |
kilohertz: 1000 hz. see hertz. |
mp3 (mpeg) |
compression format based on the MPEG video compression format. The compression is
lossy, and has many encoding parameters, including frame size (the larger, the more accurate), stereo encoding, and psy models (which simulate lost frequencies) |
Nyquist theorem |
states that the highest audible frequency is half the sampling rate |
oversampling |
filtering process that reduces the effects of digital distortion in the high frequencies
and jitter.The more times oversampling takes place (8 is common today), the less erroneous data remains. |
Real Audio |
popular compression format for streaming voice on the Internet. The compression
is very lossy, but is simple to encode, and very compact. |
sampling rate |
the number of bytes per second that represent digital audio. CD audio uses
44,100 samples per second (44.1khz); DVD-audio uses 96 khz. |