loudnesses

Loudness is a subjective perceptual property of sound. It is related to the physical measurement of sound pressure or intensity, but is not directly equivalent. Loudness is influenced by factors such as sound pressure level, frequency, and duration. For example, sounds at frequencies humans are more sensitive to will generally be perceived as louder than sounds with the same sound pressure level at less sensitive frequencies.

The relationship between sound pressure level and loudness is non-linear. A doubling of sound pressure level does not necessarily result in a doubling of perceived loudness. To quantify loudness, various scales and models have been developed. The sone is a unit of loudness, where a sound with a loudness of 1 sone is perceived to have a loudness of 40 phons. The phon is a unit of loudness level, defined such that a sound with a loudness level of X phons has the same loudness as a 1000 Hz tone with a sound pressure level of X decibels.

In audio engineering and broadcasting, loudness measurements are crucial for ensuring consistent listening experiences across different programs and platforms. Standards like ITU-R BS.1770 define algorithms for measuring integrated loudness, peak loudness, and loudness range. These measurements help to avoid extreme variations in volume that can be jarring or fatiguing for the listener. Understanding loudness is important for audio production, acoustic design, and audiometric testing.