Glossary terms: Sound

16-Bit Audio

Definition: A unit of measure that indicates the resolution of a digitised sound sample. The higher the resolution, the better the audio fidelity. 16-bit audio is the standard used for standard audio Compact Discs (CD-DA).

3D Sound

Definition: A blanket term for technologies that alter the way sound is distributed in real-world space. Spatialisation broadens the soundstage (the area in space where the sound seems to be coming from), making it more dramatic and spacious, and gives the illusion of pushing it beyond the physical location of the speakers. Positional audio uses encoded audio streams to position sounds realistically in the space around the listener when the sounds are played back on compatible equipment.

8-Bit Audio

Definition: A unit of measure that indicates the resolution of a digitised sound sample. The higher the resolution, the better the audio fidelity. Audio that is digitised using 8 bits of resolution is slightly better in fidelity than normal AM radio.

A3D

Definition: A positional audio technology and audio API developed by Aureal Semiconductor Inc. A3D enables a real-life audio experience by surrounding the listener with sounds in all three dimensions using only a single pair of ordinary speakers or headphones.

Guides: A3D

AC 97

Definition: An Intel-recommended standard for PC audio circuitry. The specification reduces noise by partitioning analogue and digital components into separate modules.

AIIF

Definition: Audio Interchange File Format: used for high end audio applications.

AU

Definition: Unix sound file format popular on the Internet.

Chorus

Definition: A doubling effect used to enhance sound.

Dolby AC-3

Definition: A perceptual digital audio coding technique capable of delivering multichannel digital surround sound. It incorporates 6 (5.1) discrete channels; each channel can carry a different signal simultaneously (left front, right front, centre, left rear, right rear, sub-woofer).

Dolby Digital

Definition: A digital audio encoding system from Dolby used in movie and home theaters. First used in 1995, Dolby Digital employs Dolby's AC-3 (Audio Coding-3) coding and compression technology and provides six channels of audio, known as 5.1 for front left, front right, front center, rear left, rear right and subwoofer.

DVD-Audio

Definition: The DVD audio-only storage format similar to CD-Audio. DVD-Audio is facing stiff competition from a number of other high fidelity audio standards.

Guides: DVD-Audio

EAX

Definition: Environmental Audio Extensions: a hardware and software audio standard developed by Creative Labs. And used originally in the company's SoundBlaster cards. EAX has subsequently become a widely supported standard offering 3D positional audio and allowing the manipulation of sounds so that they can appear to be heard in different listening environments.

Guides: EAX

FM Synthesis

Definition: Frequency Modulation Synthesis: an outdated technique for synthesising music reproduction but still widely supported to provide compatibility with older games software.

Guides: FM Synthesis

Gain

Definition: The increase in signalling power as an audio signal is boosted by an electronic device. It is measured in decibels.

General MIDI

Definition: A table of 128 standard sounds or instruments for MIDI cards and synthesisers.

Guides: General MIDI

HRTF

Definition: Head-Related Transfer Functions: Refers to the mathematics that models the way a human ear localises the direction of a sound.

MIDI

Definition: Musical Instrument Digital Interface: a specification that standardises the interface between computers and digital devices that simulate musical instruments. Rather than transmit bulky digitised sound samples, a computer generates music on a MIDI synthesiser by sending it commands just a few bytes in length. These contain all the information a sound board needs to reproduce the desired sound - the type of instrument, the pitch, duration, volume, attack, decay, etc. are all specified by the protocol. Each channel of a MIDI synthesiser corresponds to a different instrument, or "voice". Programming several channels simultaneously produces symphonic sound.

Guides: MIDI

MIDI Mapper

Definition: Windows multimedia translator for MIDI hardware and software.

MiniDisc

Definition: MD: a compact digital audio disc from Sony that comes in read-only and rewritable versions. Introduced in late 1993, the MiniDisc has been popular in Japan. The read-only 2.5in disc stores 140MB compared to 650MB on a CD, but holds the same 74 minutes worth of music due to Sony's Adaptive Transform Acoustic Coding (ATRAC) compression scheme, which eliminates inaudible portions of the signal.

MP3

Definition: Standardised as ISO-MPEG Audio Layer-3 (IS 11172-3 and IS 138-3), MP3 employs a lossy compression technique, with bits of information being discarded to allow data to be compressed into files which are relatively small in comparison with WAV files but which retain subjective CD quality.

Guides: MP3