VU meter
Encyclopedia
A VU meter is often included in audio
Sound
Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...

 equipment to display a signal level in Volume Units; the device is sometimes also called volume indicator (VI).

It is intentionally a "slow" measurement, averaging out peaks and troughs of short duration to reflect the perceived loudness
Loudness
Loudness is the quality of a sound that is primarily a psychological correlate of physical strength . 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."Loudness, a subjective measure, is often...

 of the material. It was originally developed in 1939 by the combined effort of Bell Labs
Bell Labs
Bell Laboratories is the research and development subsidiary of the French-owned Alcatel-Lucent and previously of the American Telephone & Telegraph Company , half-owned through its Western Electric manufacturing subsidiary.Bell Laboratories operates its...

 and broadcasters CBS
CBS
CBS Broadcasting Inc. is a major US commercial broadcasting television network, which started as a radio network. The name is derived from the initials of the network's former name, Columbia Broadcasting System. The network is sometimes referred to as the "Eye Network" in reference to the shape of...

 and NBC
NBC
The National Broadcasting Company is an American commercial broadcasting television network and former radio network headquartered in the GE Building in New York City's Rockefeller Center with additional major offices near Los Angeles and in Chicago...

 for measuring and standardizing the levels of telephone
Telephone
The telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...

 lines.
The typical VU scale is from −20 to +3. The rise and fall times of the meter are both 300 milliseconds, meaning that if a constant sine wave of amplitude 0 VU is applied suddenly, the meter will take 300 milliseconds to reach the 0 on the scale. It behaves as a full-wave averaging instrument, and is not optimal for measuring peak levels.

The behaviour of VU meters is defined in ANSI
Ansi
Ansi is a village in Kaarma Parish, Saare County, on the island of Saaremaa, Estonia....

 C16.5-1942, British Standard BS 6840, and IEC
International Electrotechnical Commission
The International Electrotechnical Commission is a non-profit, non-governmental international standards organization that prepares and publishes International Standards for all electrical, electronic and related technologies – collectively known as "electrotechnology"...

 60268-17.

See also

  • Audio equipment
    Audio equipment
    A piece of audio equipment is any device designed principally to reproduce, record or process sound. This includes microphones, radio receivers, AV receivers, CD players, tape recorders, amplifiers, mixing consoles, effects units and loudspeakers....

  • Crest factor
    Crest factor
    The crest factor or peak-to-average ratio or peak-to-average power ratio is a measurement of a waveform, calculated from the peak amplitude of the waveform divided by the RMS value of the waveform.C =...

  • Decibel
  • Loudness monitoring
    Loudness monitoring
    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 which many would argue is...

  • Mixing console
    Mixing console
    In professional audio, a mixing console, or audio mixer, also called a sound board, mixing desk, or mixer is an electronic device for combining , routing, and changing the level, timbre and/or dynamics of audio signals. A mixer can mix analog or digital signals, depending on the type of mixer...

  • Nominal level
    Nominal level
    Nominal level is the operating level at which an electronic signal processing device is designed to operate. The electronic circuits that make up such equipment are limited in the maximum signal they can output and the low-level internally-generated electronic noise they add to the signal...

  • Peak meter
    Peak meter
    A peak meter is a type of visual measuring instrument that indicates the instantaneous level of an audio signal that is passing through it...

  • Peak programme meter
    Peak programme meter
    A peak programme meter is an instrument used in professional audio for indicating the level of an audio signal.There are many different kinds of PPM. They fall into broad categories:...

  • Programme level
    Programme level
    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 , radio and television are to get the best experience, without excessive noise in quiet periods or distortion of loud sounds...


External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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