Loudness

volumeloudBlareloud volumevolumesamplitudeblaringdynamicslouderloudest
In acoustics, loudness is the subjective perception of sound pressure.wikipedia
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Sone

Sones
Others, such as ISO 532A (Stevens loudness, measured in sones), ISO 532B (Zwicker loudness), DIN 45631 and ASA/ANSI S3.4, have a more general scope and are often used to characterize loudness of environmental noise. Historically Sone (loudness N) and Phon (loudness level L) units have been used to measure loudness.
The sone is a unit of loudness, the subjective perception of sound pressure.

Psychoacoustics

psychoacousticpsychoacoustic modelperceptual coding
The study of apparent loudness is included in the topic of psychoacoustics and employs methods of psychophysics.
In addition, the ear has a nonlinear response to sounds of different intensity levels; this nonlinear response is called loudness.

Acoustics

acousticacousticianacoustical
In acoustics, loudness is the subjective perception of sound pressure.
The loudness of these disturbances is related to the sound pressure level (SPL) which is measured on a logarithmic scale in decibels.

LKFS

EBU R128ITU-R BS.1770LUFS
Some definitions, such as ITU-R BS.1770 refer to relative loudness of different segments of electronically reproduced sounds, such as for broadcasting and cinema. Filters such as A-weighting and LKFS attempt to compensate measurements to correspond to loudness as perceived by the typical human.
Loudness, K-weighted, relative to full scale (LKFS) is a loudness standard designed to enable normalization of audio levels for delivery of broadcast TV and other video.

A-weighting

dBAA-weighteddB(A)
Filters such as A-weighting and LKFS attempt to compensate measurements to correspond to loudness as perceived by the typical human.
A-weighting is applied to instrument-measured sound levels in an effort to account for the relative loudness perceived by the human ear, as the ear is less sensitive to low audio frequencies.

Equal-loudness contour

equal-loudness contoursFletcher-Munson curvesFletcher–Munson curves
The sensitivity of the human ear changes as a function of frequency, as shown in the equal-loudness graph.
An equal-loudness contour is a measure of sound pressure (dB SPL), over the frequency spectrum, for which a listener perceives a constant loudness when presented with pure steady tones.

ReplayGain

Replay Gain
ReplayGain is a proposed standard published by David Robinson in 2001 to measure the perceived loudness of audio in computer audio formats such as MP3 and Ogg Vorbis.

Critical band

critical bandsAuditory filters
Contemporary standards for measurement of loudness are based on summation of energy in critical bands.
Masking phenomena have wide implications, ranging from a complex relationship between loudness (perceptual frame of reference) and intensity (physical frame of reference) to sound compression algorithms.

Audio normalization

normalizationnormalizednormalisation
Loudness normalization is a specific type of audio normalization that equalizes perceived level such that, for instance, commercials do not sound louder than television programs.
Loudness normalization adjusts the recording based on perceived loudness.

Phon

Historically Sone (loudness N) and Phon (loudness level L) units have been used to measure loudness.
The phon is a unit of loudness for pure tones.

Sound pressure

sound pressure levelSPLacoustic pressure
In acoustics, loudness is the subjective perception of sound pressure. Loudness, a subjective measure, often confused with physical measures of sound strength such as sound pressure, sound pressure level (in decibels), sound intensity or sound power.

Decibel

dBdecibelsbel
Loudness, a subjective measure, often confused with physical measures of sound strength such as sound pressure, sound pressure level (in decibels), sound intensity or sound power.

Loudness compensation

loudness switchloudness switches
The "loudness" control associated with a loudness compensation feature on some consumer stereos alters the frequency response curve to correspond roughly with the equal loudness characteristic of the ear.
This is intended to be used at low listening levels, to compensate for the fact that as the loudness of audio decreases, the ear's lower sensitivity to extreme high and low frequencies may cause these signals to fall below threshold.

Amplitude

peak-to-peakintensityvolume
Historically, loudness was measured using an "ear-balance" audiometer in which the amplitude of a sine wave was adjusted by the user to equal the perceived loudness of the sound being evaluated.
Loudness is related to amplitude and intensity and is one of the most salient qualities of a sound, although in general sounds can be recognized independently of amplitude.

Dynamics (music)

crescendodynamicspianissimo
In music, the dynamics of a piece is the variation in loudness between notes or phrases.

Loudness war

dynamic rangeLoudness Warsbrickwalled
Increasing loudness was first reported as early as the 1940s, with respect to mastering practices for 7" singles. The maximum peak level of analog recordings such as these is limited by varying specifications of electronic equipment along the chain from source to listener, including vinyl and Compact Cassette players. The issue garnered renewed attention starting in the 1990s with the introduction of digital signal processing capable of producing further loudness increases.

Mary Florentine

Softness imperception, a term coined by Mary Florentine around 2002, proposes that some listeners with sensorineural hearing loss may exhibit a normal rate of loudness growth, but instead have an elevated loudness at their threshold.

Loudness monitoring

CBS Loudness Meterloudness meteringloudness monitors
Relative loudness monitoring in production is measured in accordance with ITU-R BS.1770 in units of LKFS.
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.

Subjectivity

subjectivesubjectivelysubjectivities
In acoustics, loudness is the subjective perception of sound pressure.

Psychophysics

psychophysicalpsychophysicistHistory of psychophysics
The study of apparent loudness is included in the topic of psychoacoustics and employs methods of psychophysics.

Sound intensity

sound levelintensitySound intensity level
Loudness, a subjective measure, often confused with physical measures of sound strength such as sound pressure, sound pressure level (in decibels), sound intensity or sound power.

Sound power

Sound power levelSound energy fluxacoustic power
Loudness, a subjective measure, often confused with physical measures of sound strength such as sound pressure, sound pressure level (in decibels), sound intensity or sound power.

Stevens's power law

Stevens' power law1961 paperSteven's Law
The relationship between SPL and loudness of a single tone can be approximated by Stevens's power law in which SPL has an exponent of 0.67.

Audiometer

Historically, loudness was measured using an "ear-balance" audiometer in which the amplitude of a sine wave was adjusted by the user to equal the perceived loudness of the sound being evaluated.

Sensorineural hearing loss

sensorineural deafnesssensorineuralSensorineural hearing impairment
When sensorineural hearing loss (damage to the cochlea or in the brain) is present, the perception of loudness is altered.