A peak meter is a type of

measuring instrument A measuring instrument is a device to measure a physical quantity. In the physical sciences, quality assurance, and engineering, measurement is the activity of obtaining and comparing physical quantities of real-world objects and events. Est ...

that indicates visually the instantaneous level of an

audio Audio most commonly refers to sound, as it is transmitted in signal form. It may also refer to: Sound * Audio signal, an electrical representation of sound *Audio frequency, a frequency in the audio spectrum * Digital audio, representation of sou ...

signal that is passing through it (a sound level meter). In

sound reproduction Sound recording and reproduction is the electrical, mechanical, electronic, or digital inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. The two main classes of sound recording ...

, the meter, whether peak or not, is usually meant to correspond to the perceived

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 ...

of a particular signal. 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-reading electrical instrument or

meter The metre (British spelling) or meter (American spelling; see spelling differences) (from the French unit , from the Greek noun , "measure"), symbol m, is the primary unit of length in the International System of Units (SI), though its pref ...

is one which measures the

peak Peak or The Peak may refer to: Basic meanings Geology * Mountain peak ** Pyramidal peak, a mountaintop that has been sculpted by erosion to form a point Mathematics * Peak hour or rush hour, in traffic congestion * Peak (geometry), an (''n''-3)-di ...

value of a waveform, rather than its

mean There are several kinds of mean in mathematics, especially in statistics. Each mean serves to summarize a given group of data, often to better understand the overall value (magnitude and sign) of a given data set. For a data set, the '' ari ...

value or RMS value. As an example, when making

audio recording Sound recording and reproduction is the electrical, mechanical, electronic, or digital inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. The two main classes of sound recording t ...

s it is desirable to use a recording level that is just sufficient to reach the maximum capability of the recorder at the loudest sounds, regardless of the average sound level. A peak-reading meter is typically used to set the recording level.

Implementation

In modern audio equipment, peak meters are usually made up of a series of

LED A light-emitting diode (LED) is a semiconductor Electronics, device that Light#Light sources, emits light when Electric current, current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy i ...

s (small lights) that are placed in a vertical or horizontal bar and lit up sequentially as the signal increases. They typically have ranges of green, yellow, and red, to indicate when a signal is starting to overload. A meter can 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 Pressure measurement is the measurement of an applied force by a fluid ( liquid or gas) on a surface. Pressure is typically measured in units of force per unit of surface area. Many techniques have been developed for the measurement of pres ...

on a

bicycle pump A bicycle pump is a type of positive-displacement air 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 Pre ...

), or by other means. Older equipment used actual

moving parts Machines include both fixed and moving parts. The moving parts have controlled and constrained motions. Moving parts are machine components excluding any moving fluids, such as fuel, coolant or hydraulic fluid. Moving parts also do not include ...

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 milliseconds 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, a peak meter 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 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 ...

s are actually closer to the human ear's perception of sound level because the response time was intentionally slow - around 300 milliseconds, 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.

References

{{DEFAULTSORT:Peak Meter Measuring instruments

Implementation

See also

References