Loudness monitoring of

programme levels {{Unreferenced, date=November 2009 Programme level refers to the signal level that an audio source is transmitted or recorded at, and is important in audio if listeners of Compact Discs (CDs), radio and television are to get the best experience, ...

is needed in

radio Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a tr ...

and

television Television, sometimes shortened to TV, is a telecommunication medium for transmitting moving images and sound. The term can refer to a television set, or the medium of television transmission. Television is a mass medium for advertising, ...

broadcasting Broadcasting is the distribution of audio or video content to a dispersed audience via any electronic mass communications medium, but typically one using the electromagnetic spectrum (radio waves), in a one-to-many model. Broadcasting began wi ...

, as well as in

audio post production Audio post production is all stages of audio production relating to sound produced and synchronized with moving picture (film, television, or video). It involves sound design, sound effects, Foley, ADR, sound editing, audio mixing, mastering e ...

. Traditional methods of measuring signal levels, such as the

Peak programme meter A peak programme meter (PPM) is an instrument used in professional audio that indicates the level of an audio signal. Different kinds of PPM fall into broad categories: *True peak programme meter. This shows the peak level of the waveform no ...

and

VU meter A volume unit (VU) meter or standard volume indicator (SVI) is a device displaying a representation of the signal level in audio equipment. The original design was proposed in the 1940 IRE paper, ''A New Standard Volume Indicator and Reference Lev ...

, do not give the subjectively valid measure of

loudness In acoustics, loudness is the subjective perception of sound pressure. More formally, it is defined as, "That attribute of auditory sensation in terms of which sounds can be ordered on a scale extending from quiet to loud". The relation of ph ...

that many would argue is needed to optimise the listening experience when changing channels or swapping disks. The need for proper loudness monitoring is apparent in the

loudness war The loudness war (or loudness race) is a trend of increasing audio levels in recorded music, which reduces audio fidelity and—according to many critics—listener enjoyment. Increasing loudness was first reported as early as the 1940s, with ...

that is now found everywhere in the audio field, and the extreme compression that is now applied to

Loudness meters

Meters have been introduced that aim to measure the human perceived loudness by taking account of the

equal-loudness contours An equal-loudness contour is a measure of sound pressure level, over the frequency spectrum, for which a listener perceives a constant loudness when presented with pure steady tones. The unit of measurement for loudness levels is the phon an ...

and other factors, such as audio spectrum, duration, compression and intensity. One such device was developed by

CBS Laboratories CBS Laboratories or CBS Labs (later known as the CBS Technology Center or CTC) was the technology research and development organization of the CBS television network. Innovations developed at the labs included many groundbreaking broadcast, indust ...

in the 1980s. Complaints to broadcasters about the intrusive level of interstitials programs (advertisements, commercials) has resulted in projects to develop such meters. Based on loudness metering, many manufacturers have developed real-time audio processors that adjust the audio signal to match a specified target loudness level that preserves volume consistency at home listeners.

EBU Mode meters

In August 2010, the European Broadcasting Union published a new metering specificatio
EBU Tech 3341
which builds on ITU-R BS.1770. To make sure meters from different manufacturers provide the same reading in LUFS units, EBU Tech 3341 specifies the ''EBU Mode'', which includes a Momentary (400ms), Short term (3s) and Integrated (from start to stop) meter and a set of audio signals to test the meters.EBU Tech 3341 Loudness Metering: ‘EBU Mode’ metering to supplement loudness normalisation in accordance with EBU R 128
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References

External links

EBU Tech 3341 audio test signalsITU-R BS.1770: Algorithms to measure audio programme loudness and true-peak audio levelEBU publishes loudness test material
* Audio engineering Broadcast engineering Sound production technology Sound recording {{Sound-tech-stub

Loudness meters

EBU Mode meters

See also

References

External links