Luidheid

Luidheid is the perceptual quality of sound that describes how loud a sound seems to a listener. It is a psychoacoustic attribute, arising from the way the auditory system analyzes amplitude, frequency content and temporal aspects rather than from a single physical measurement alone.

To quantify luidheid, researchers use scales such as phons and sones. A phon represents loudness level at a given frequency based on equal-loudness contours, while a sone provides a more linear perceptual scale: by definition, one sone equals the loudness of a 1 kHz tone at 40 dB SPL, and larger values denote greater perceived loudness.

Loudness depends on several factors: sound pressure level, spectral composition, duration, and masking phenomena in which certain frequencies make others harder to hear. Equal-loudness contours show that the same physical intensity can be perceived as louder or softer depending on frequency. Individual hearing abilities, age, and prior exposure also shape luidheid perception.

Practically, luidheid is inferred from objective measures such as SPL and spectral content, and from standardized loudness metrics used in audio engineering. In broadcasting and music production, loudness normalization often employs integrated measures (for example LUFS) to maintain consistent perceived loudness across programs.

Applications and considerations: understanding luidheid is important for speech intelligibility, hearing protection, and comfortable acoustic design in rooms and workplaces. The term is mainly used in Dutch-language acoustics and psychoacoustics literature to refer to the perceived intensity of sound.