Peak meter
Encyclopedia
A peak meter is a type of visual measuring instrument
that 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.
In modern audio equipment, peak meters are usually made up of a series of LED
s (small lights) that are placed in a vertical or horizontal bar and lit up sequentially as the signal increases. There are many variations on how this is implemented. They typically have ranges of green, yellow, and red, to indicate when a signal is starting to overload
.
The term "peak" is used to denote the meter's ability, regardless of the type of visual display, to indicate the highest output level at any instant.
A peak meter can also be implemented with a classic moving needle device such as those on older analog equipment (similar in appearance in some ways to a pressure gauge on a bicycle pump
), or by other means. Older equipment used actual moving parts
instead of lights to indicate the audio level. Because of the mass of the moving parts and mechanics, the response time of these older meters could have been anywhere from a few millisecond
s to a second or more. Thus, the meter might not ever accurately reflect the signal at every instant of time, but the constantly changing level, combined with the slower response time, led to more of an "average" indication.
By comparison, "peak" type metering is designed to respond so quickly that the meter display reacts in exact proportion to the voltage of the audio signal. This can be useful in many applications, but the human ear works much more like an average meter than a peak meter. The analog VU meter
s are actually closer to the human ear's perception of sound level, because the response time was intentionally slow - around 300 miliseconds, http://www.propellerheads.se/substance/discovering-reason/index.cfm?article=part3&fuseaction=get_article and thus, many audio engineers and sound professionals prefer to use older analog style metering because it more accurately relates to what a human listener will experience in terms of relative loudness.
Measuring instrument
In the physical sciences, quality assurance, and engineering, measurement is the activity of obtaining and comparing physical quantities of real-world objects and events. Established standard objects and events are used as units, and the process of measurement gives a number relating the item...
that indicates the instantaneous level of an 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...
signal that is passing through it (a sound level meter
Sound level meter
Sound level meters measure sound pressure level and are commonly used in noise pollution studies for the quantification of almost any noise, but especially for industrial, environmental and aircraft noise. However, the reading given by a sound level meter does not correlate well to...
). In sound reproduction, the meter, whether peak or not, is usually meant to correspond to 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 a particular signal.
In modern audio equipment, peak meters are usually made up of a series of LED
LEd
LEd is a TeX/LaTeX editing software working under Microsoft Windows. It is a freeware product....
s (small lights) that are placed in a vertical or horizontal bar and lit up sequentially as the signal increases. There are many variations on how this is implemented. They typically have ranges of green, yellow, and red, to indicate when a signal is starting to overload
Overload
-Bands:* Overload * Overload * Overload -Albums:*Overload *Overload *Overload -Songs:*Overload , a dance song by Voodoo and Serano...
.
The term "peak" is used to denote the meter's ability, regardless of the type of visual display, to indicate the highest output level at any instant.
A peak meter can also be implemented with a classic moving needle device such as those on older analog equipment (similar in appearance in some ways to a pressure gauge on a bicycle pump
Bicycle pump
A bicycle pump is a type of positive-displacement pump specifically designed for inflating bicycle tires. It has a connection or adapter for use with one or both of the two most common types of valves used on bicycles, Schrader or Presta...
), or by other means. Older equipment used actual moving parts
Moving parts
The moving parts of a machine are those parts of it that move. Machines comprise both moving and fixed parts. The moving parts have controlled and constrained motions....
instead of lights to indicate the audio level. Because of the mass of the moving parts and mechanics, the response time of these older meters could have been anywhere from a few millisecond
Millisecond
A millisecond is a thousandth of a second.10 milliseconds are called a centisecond....
s to a second or more. Thus, the meter might not ever accurately reflect the signal at every instant of time, but the constantly changing level, combined with the slower response time, led to more of an "average" indication.
By comparison, "peak" type metering is designed to respond so quickly that the meter display reacts in exact proportion to the voltage of the audio signal. This can be useful in many applications, but the human ear works much more like an average meter than a peak meter. The analog VU meter
VU meter
A VU meter is often included in audio equipment to display a signal level in Volume Units; the device is sometimes also called volume indicator ....
s are actually closer to the human ear's perception of sound level, because the response time was intentionally slow - around 300 miliseconds, http://www.propellerheads.se/substance/discovering-reason/index.cfm?article=part3&fuseaction=get_article and thus, many audio engineers and sound professionals prefer to use older analog style metering because it more accurately relates to what a human listener will experience in terms of relative loudness.
See also
- Peak programme meterPeak programme meterA 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:...
(A quasi-peak meter originally developed by the BBCBBCThe British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...
) - VU meterVU meterA VU meter is often included in audio equipment to display a signal level in Volume Units; the device is sometimes also called volume indicator ....
- Audio equipmentAudio equipmentA 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....
- Decibel#Acoustics
- Various freeware meters for accurate recording: http://www.darkwood.demon.co.uk/PC/meter.html