Fig. 1: The historical Fletcher-Munson equal-loudness contours of 1933 - Phons are labelled in blue.

The phon is a unit of perceived loudness, which is a subjective measure of the strength (not intensity) of a sound. At a frequency of 1 kHz, 1 phon is defined to be equal to 1 dB of sound pressure level above the nominal threshold of hearing, the sound pressure level SPL of 20 µPa (micropascals) = 2 · 10^-5 pascal (Pa). Our ears as sensors cannot convert sound intensities and powers, they can only use the sound pressure. Fairly accurate trace of original Fletcher-Munson equal loudness contours with threshold of audibility, threshold of pain, phons labels. ... Fairly accurate trace of original Fletcher-Munson equal loudness contours with threshold of audibility, threshold of pain, phons labels. ... The definition, agreement and practical use of units of measurement have played a crucial role in human endeavour from early ages up to this day. ... PSYCHOLOGY In psychology and the cognitive sciences, perception is the process of acquiring, interpreting, selecting, and organizing sensory information. ... Loudness is the quality of a sound which is high in volume (amplitude, or sound pressure). ... This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... Strength can mean: Physical strength of organisms means (especially the muscles of most metazoa) of locomotion and movement Strength of materials in physics, engineering and materials science Strength is a rap compilation presented by Asiatic Warriors The word strengths is one of the longest English words with one syllable. ... The sound intensity, I, (acoustic intensity) is defined as the sound power Pac per unit area A. The usual context is the measurement of sound intensity in the air at a listeners location. ... Jump to: navigation, search A schematic representation of hearing. ... Sine waves of various frequencies; the lower waves have higher frequencies than those above. ... A kilohertz (kHz) is a unit of frequency equal to 1,000 hertz (1,000 cycles per second). ... The decibel (dB) is a measure of the ratio between two quantities, and is used in a wide variety of measurements in acoustics and electronics. ... Jump to: navigation, search Sound pressure level (SPL) or sound level Lp is a logarithmic measure of a particular noise relative to a reference noise source. ... Fig. ...

At other frequencies, the phon departs from the decibel, but is related to it by a frequency weighting curve (equal-loudness contour) that reflects the frequency response of human hearing. The standard curve for human hearing is the A-weighted curve (the equal-loudness contour for a 40 dB stimulus at 1 kHz), but others are in use. The A, B, C, and D weighting curves A weighting filter or weighting curve is a type of linear filter used in audio signal processing to approximate the response of the sound pressure level of the human ear. ... Jump to: navigation, search The old Fletcher-Munson equal-loudness curves from 1933. ... Frequency response is the measure of any systems response to frequency, but is usually used in connection with electronic amplifiers and similar systems, particularly in relation to audio signals. ... Jump to: navigation, search Hearing, or audition, is one of the traditional five senses, and refers to the ability to detect sound. ... The A, B, C, and D weighting curves A weighting filter or weighting curve is a type of linear filter used in audio signal processing to approximate the response of the sound pressure level of the human ear. ...

The "unit" phon has been largely replaced by the dB(A) (A-weighted decibel), though many old textbooks and instructors continue to use the phon. The A-weighting curve dB(A) or dBA stands for decibels adjusted. ...

See also

• sone

The sone is a unit of perceived loudness after a proposal of S. Smith Stevens in 1936. ...

External links

• Fletcher-Munson curves are different from the new Robinson-Dadson curves