ääniintensiteetti

Ääniintensiteetti, often translated as sound intensity, is a physical quantity that measures the power carried by sound waves per unit area in a direction perpendicular to that area. It is a measure of the energy flow of a sound wave. The standard unit for sound intensity in the International System of Units (SI) is watts per square meter (W/m²).

Sound intensity is directly proportional to the square of the pressure amplitude of the sound wave and inversely proportional to the acoustic impedance of the medium. This means that for a given medium, a sound wave with a larger pressure variation will carry more energy. The intensity also depends on the frequency of the sound.

A common way to express sound intensity is using the logarithmic decibel (dB) scale. This scale relates the measured sound intensity to a reference intensity, typically the threshold of human hearing. The decibel scale is used because the range of sound intensities that humans can perceive is very wide, and a logarithmic scale provides a more manageable representation. While sound intensity describes the physical power of a sound wave, sound pressure level is often used in practical acoustics and is related to the pressure fluctuations caused by the sound wave.