Pink Noise

Pink noise is a random signal with equal energy per octave band, meaning its spectral density decreases at 3 dB per octave (inversely proportional to frequency). It sounds "balanced" to human ears because our auditory system perceives in logarithmic frequency bands. Pink noise is the standard test signal for room acoustic measurements requiring steady-state excitation, including background noise masking levels, loudspeaker equalization, and sound insulation testing per ISO 16283. When played through a loudspeaker in a room, pink noise produces a flat spectrum on an octave-band analyzer if the system is correctly equalized. It is also used as the reference for noise criteria assessments (NR, NC, RC curves). Pink noise generators are built into most acoustic measurement systems. The term distinguishes it from white noise, which has equal energy per hertz and sounds brighter or hissy.