psychoakustikka

Psychoacoustics, sometimes referred to as psychoakustikka in Finnish-language literature, is the scientific study of how humans perceive sound. It investigates the relationships between physical sound properties—such as frequency, amplitude, and spectral composition—and perceptual attributes like pitch, loudness, timbre, and duration, as well as spatial hearing and auditory scene analysis.

Key phenomena include loudness perception and its nonlinearity, governed by equal-loudness contours and the phon/sones scales; pitch perception and its variations with frequency and complex tones; timbre and spectral balance; and auditory masking, where one sound makes another harder to hear. The concept of critical bands describes the frequency regions that are processed together in the auditory system.

Psychoacoustic research uses behavioral experiments, such as loudness matching and detection threshold tasks, to build models of perception. Foundational work by Fletcher and Munson on equal-loudness curves and later models (e.g., Zwicker's critical-band theory) shaped modern understanding and applications. Psychoacoustic models underpin many audio-processing technologies.

Applications include perceptual audio coding (how codecs remove inaudible components), hearing aids and cochlear implants, sound design and virtual acoustics, room and architectural acoustics, and auditory display systems. The field intersects psychology, neuroscience, signal processing, and acoustics, and continues to inform both theoretical understanding and practical engineering.