including the disbanding of the Street Crime Unit.
Anger about Diallo’s death, nevertheless, would
continue well into the twenty-first century.
Further Reading
Diallo, Kadiatou, with Craig Wolff.My Heart Will
Cross This Ocean: My Stor y, My Son, Amadou. New
York: One World, 2003.
Fireside, Bryna J.The Trial of the Police Officers in the
Shooting Death of Amadou Diallo: A Headline Court
Case. Berkeley Heights, N.J.: Enslow, 2004.
Thomas Tandy Lewis
See also African Americans; Los Angeles riots;
Louima torture case; Police brutality; Race relations;
Sharpton, Al.
Digital audio
Definition The representation of sound waves as
binary data, which in this form can be stored,
transmitted, edited, and ultimately converted
back into physical sound waves for playback into
speakers and similar devices
At the beginning of the 1990’s, the digital audio compact
disc (audio CD), which had just replaced analog media
such as vinyl records and cassette tapes as the primar y con-
sumer audio format, achieved unparalleled popularity. By
the end of the decade, several trends, including the in-
creased use of personal computers as both audio playback
devices and audio editing platforms, the widespread distri-
bution of compressed audio over the Internet, and the gen-
eral availability of low-cost CD recorders, had revolution-
ized the music industr y, pointing to even more rapid
changes in the twenty-first centur y.
Although not as popular as audio CDs, several other
digital audio formats were in use in the early 1990’s.
Digital audio tape (DAT), which had been intro-
duced by Sony in 1987, was used primarily for re-
cording and archiving. DAT recorders could equal
or slightly exceed the resolution levels of audio
CDs (16-bit stereo, 44.1 kilohertz). Made available
in 1991, Alesis digital audio tape (ADAT), another
format, allowed eight tracks to be recorded at the
same time. Sony’s compact MiniDisc, introduced in
1992, offered compressed digital audio recording
but did not become as popular with consumers as
audio CDs.
During this period, due to severe limitations on
hard drive capacity and speed, digital audio play-
back on personal computers was typically formatted
for much lower resolution levels than either audio
CDs or DAT. Various file formats were developed for
personal computers, the two most popular being
waveform audio format (WAV) and audio inter-
change file format (AIFF). WAV, developed by
Microsoft and International Business Machines
(IBM), was used primarily with Microsoft’s operat-
ing systems, and the AIFF was used on Apple
Macintosh computers. Unlike the Red Book audio
format used for audio CDs, the AIFF and WAV for-
mats could store information at different bit depths
and sample rates, and as either mono or stereo. This
made such formats ideal for lower-resolution play-
back, including audio for games.
As a way around the inherent limitations of per-
sonal computers, external devices and supplemen-
tal sound expansion cards were developed. Sound
Blaster expansion cards, produced by Creative Labs,
were very popular additions to Microsoft-compati-
ble computers. Along with providing digital file out-
put, these sound cards could also provide musical in-
strument digital interface (MIDI) support. MIDI, an
audio technology developed in the 1980’s, was a pro-
tocol that allowed computer programs to send play-
back instructions to musical synthesizers, which at
first were external units connected through inter-
faces and cables. During the 1990’s, MIDI playback
became more routinely associated with software syn-
thesizers, without completely replacing external
musical playback and input devices (usually music
keyboards). In 1994, MIDI support was added to Ap-
ple’s QuickTime media player, allowing music to be
added to digital movies without great increases in
file sizes.Accelerated Change In the second half of the
1990’s, digital audio played an important role in the
availability of multimedia on the Internet, the de-
centralization of the music industry, and increased
options available to consumers. The digital video
disc (DVD), or “digital versatile disc,” announced in
1995, is also capable of storing digital audio, which
was part of the format specification for the disc. With
room for up to 4.7 gigabytes of data, the new format
was capable of much longer sound files and higher
levels of resolution than previous formats.
The digital audio workstation (DAW) became256 Digital audio The Nineties in America