Äänipainetason

Äänipainetaso, often abbreviated as SPL or L, is a logarithmic measure of the effective sound pressure of a sound relative to a reference value. It is used to quantify how loud a sound is perceived. The standard reference pressure in air is 20 micropascals (µPa), which is approximately the threshold of human hearing at 1 kHz. The unit of äänipainetaso is the decibel (dB).

The formula for calculating SPL is L = 20 * log10(p / p0), where 'p' is the measured sound pressure and 'p0' is the reference sound pressure. Because the decibel scale is logarithmic, a doubling of sound pressure does not correspond to a doubling of decibels. Instead, a 3 dB increase typically represents a doubling of sound energy or intensity, while a 10 dB increase is perceived as roughly twice as loud.

Äänipainetaso measurements are crucial in various fields, including acoustics, audio engineering, environmental noise monitoring, and occupational safety. Different weighting filters, such as A-weighting (dBA) and C-weighting (dBC), are often applied to SPL measurements to better reflect how the human ear perceives loudness at different frequencies. A-weighting is most commonly used for general noise measurements as it approximates the human ear's sensitivity at lower sound levels.