The loudest sound pressure level that a device can generate or tolerate.

A facility found mostly in live-sound mixing consoles used to create separate mixes which can be sent to many different output destinations. Essentially, a Matrix creates 'a mix of mixes' since derived from pre-mixed output signals such as subgroups, auxes or main outputs. This is in contrast to the normal console mixing facilities which are derived from input channel signals. A matrix can be any size, and is usually described in terms of numbers of inputs and outputs, such as 2x2 or 8x8, or 8x6 etc with a level control at each junction of the matrix so that the desired amount of any source can be sent to any output - and it is this feature that makes a Matrix more versatile than a conventional subgrouping system. Matrix sends might be used to create appropriate feeds for disparate destinations like PA front fills, green-room foldback, camera recorders, and so on.

Traditionally the sequencing of individual recordings to form a cohesive album of material, and to apply corrective equalisation and dynamics processing to ensure a consistent sound character and to optimise playback on the widest possible range of sound systems. Appropriate signal processing may also be applied to make the mastered material suitable for its intended medium (such as controlling transient peaks and dynamics and mono-ing the bass for vinyl records, etc).

A device which controls slave devices. Often used to refer to synchronised recorders, or digital clocking devices.

Also called magnetic compensation (which is usually a more accurate description). A means of restricting the radiation range of the stray magnetic field from a drive unit’s permanent magnet which might otherwise interfere with the correct operation of moving-coil meters or CRT television monitors. While it is possible to enclose a magnet in a soft-metal case to prevent a stray magnetic field this becomes very expensive for large magnets, and so a more common approach is to affix additional small external magnets with opposite polarities to cancel out the unwanted stray field.

Multichannel Audio Digital Interface. Originally specified by the Audio Engineering Society (AES) as AES10 in 1991. This unidirectional digital audio interface shares the same core 24-bit audio and status data format as AES3, but with different 'wrapping' to contain 56 or 64 synchronous channels at base sample rates, or 28/32 channels at 96kHz. It can be conveyed over unbalanced coaxial cables, or via optical fibres.

Abbreviation for milli, meaning a multiplier of 1/1000 (one thousandth). Used as a prefix to other values to indicate magnitude, eg. 1mA = 0.001A.

The standard measurement of loudness, as used on Loudness Meters corresponding to the ITU-TR BS1770 specification. the acronym stands for 'Loudness Units (relative to) Full Scale. Earlier versions of the specification used LKFS instead, and this label remains in use in America. The K refers to the 'K-Weighting' filter used in the signal measurement process. (See this article on the loudness metering concept.)

The lower portion of the audible frequency spectrum, typically denoting frequencies below about 1kHz

The practice of trying to make each new commercial music release sound subjectively louder than any previous release, on the misguided notion that louder is more exciting and results in more sales. A relationship between the average loudness of 45rpm singles and sales was noticed in America from jukebox plays, and that led to the first loudness war. However, the advent of the CD really ramped up the situation, with music becoming ever-more dynamically compressed to squeeze the average level higher and higher towards the 0dBFS peak level. This desctructive trend is, thankfully, now being slowly reversed with the ubiquity of loudness normalisation adopted by most online audio streaming services and broadcasters.