Pink noise distributes equal energy per octave, rolling off 3 dB per octave versus white noise

Pink noise (also called 1/f noise) has a spectrum whose energy drops as frequency rises — specifically a 3 dB attenuation per octave. Whereas white noise has equal energy per hertz, pink noise has equal energy per octave: each successively higher octave spans twice the raw frequency band, and pink noise spreads the same energy across that wider band, producing the constant 3 dB roll-off. Because octave-based energy distribution matches how humans hear, pink noise is the standard test signal — paired with a spectrum analyzer — for measuring and correcting the frequency response of a room or sound system.

Examples

A spectrum analyzer fed pink noise through a PA in a venue shows a roughly flat perceived response when the room is well-tuned; peaks and dips reveal room modes to be EQ’d out. White noise through the same rig would look bright/tilted because it weights high frequencies more per octave.

Assessment

State the per-octave energy difference between white and pink noise, give pink noise’s dB-per-octave slope, and explain why pink noise is preferred for room-response measurement.