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EBU R 128 is a recommendation for loudness normalisation and maximum level of audio signals. It is primarily followed during audio mixing of television and radio programmes and adopted by broadcasters to measure and control programme loudness. [1]
Loudness monitoring of programme levels is needed in radio and television broadcasting, as well as in audio post production.Traditional methods of measuring signal levels, such as the peak programme meter and VU meter, do not give the subjectively valid measure of loudness that many would argue is needed to optimise the listening experience when changing channels or swapping disks.
For compliance purposes, readings with an ANSI Type 2 sound level meter and dosimeter are considered to have an accuracy of ±2 dBA, while a Type 1 instrument has an accuracy of ±1 dBA. A Type 2 meter is the minimum requirement by OSHA for noise measurements and is usually sufficient for general-purpose noise surveys. The Type 1 meter is ...
Another type of normalization is based on a measure of loudness, wherein the gain is changed to bring the average loudness to a target level. This average may be approximate, such as a simple measurement of average power (e.g. RMS), or more accurate, such as a measure that addresses human perception e.g. that defined by EBU R128 and offered by ReplayGain, Sound Check and GoldWave.
Noise measurement can also be part of a test procedure using white noise, or some other specialized form of test signal.In audio systems and broadcasting, specific methods are used to obtain subjectively valid results in order that different devices and signal paths may be compared regardless of the inconsistent spectral distribution and temporal properties of the noise that they generate.
The first signal report format code may have been QJS. [citation needed]The U.S. Navy used R and K signals starting in 1929. [citation needed]The QSK code was one of the twelve Q Codes listed in the 1912 International Radiotelegraph Convention Regulations, but may have been in use earlier.
A peak meter is a type of measuring instrument that visually indicates the instantaneous level of an audio signal that is passing through it (a sound level meter). In sound reproduction , the meter, whether peak or not, is usually meant to correspond to the perceived loudness of a particular signal.
The crest factor, which is the difference between the signal's peak and its average power, [31] is on occasions considered as a basis for the measure of micro-dynamics, for instance in the TT Dynamic Range Meter plug-in. [32] Finally, R 128 LRA has been repeatedly considered as a measure of macro-dynamics or dynamics in the musical sense.