Painotuskäyrät

Painotuskäyrät, or weighting curves, are mathematical functions used to adjust the perceived loudness of a sound signal at different frequencies. In audio engineering and acoustics, human hearing is not equally sensitive to all frequencies. We are most sensitive to frequencies in the mid-range, typically between 1 kHz and 4 kHz, and less sensitive to very low and very high frequencies. Weighting curves are designed to account for this characteristic of human hearing.

The most common weighting curve is the A-weighting curve, denoted as dBA. This curve approximates the frequency response of the human ear at moderate sound pressure levels. It attenuates low frequencies significantly and, to a lesser extent, high frequencies, while leaving the mid-range frequencies largely unaffected. A-weighting is widely used for measuring sound levels in environmental noise assessments, industrial noise control, and in applications where the subjective loudness is of primary concern.

Other weighting curves exist, such as the B-weighting, C-weighting, and Z-weighting curves. The B-weighting curve, once used for moderate sound levels, is now rarely employed. The C-weighting curve (dBC) is less aggressive in attenuating low frequencies than A-weighting and is often used for measuring peak sound levels or when dealing with high-intensity noise. The Z-weighting curve, derived from the IEC 61672 standard, represents a flat frequency response, meaning it does not apply any weighting. It is used as a reference for calibrating other weighting filters and for scientific measurements where the actual sound pressure level is required without psychoacoustic influence. The selection of the appropriate weighting curve depends on the specific application and the type of sound being measured.