Simple Explanation

A way of describing how quickly a signal decreases in level (attenuates) above or below a certain frequency—typically used in filters and crossovers.

Concise Technical Definition

A logarithmic measurement of filter steepness, where attenuation increases by a defined number of decibels (dB) for each doubling (octave) of frequency. Common values are 6, 12, 18, and 24 dB/octave, corresponding to first-, second-, third-, and fourth-order filters.

Layman-Friendly Analogy

Imagine a hill getting steeper as you climb it—dB/octave is how steep that hill gets. A gentle slope (6 dB/octave) is easy to walk; a steep slope (24 dB/octave) is more abrupt.

Industry Usage Summary

Used in audio processing, particularly in crossover networks and equalizers, to describe how sharply a signal is reduced past a certain cutoff frequency. A 6 dB/octave slope reduces the signal gently; a 24 dB/octave slope does so more abruptly. Steeper slopes like 50 dB/octave are found in precision filters such as brick-wall designs.

Engineering Shortcut

A first-order filter attenuates 6 dB for every octave beyond the cutoff; a fourth-order filter attenuates 24 dB per octave. Steeper filters require more components and can introduce phase shifts.

Full Technical Explanation

dB/octave is a logarithmic expression that quantifies the rate of signal attenuation in filters. One octave represents a doubling or halving of frequency. A slope of 6 dB/octave (first-order) means the signal reduces by 6 dB every time the frequency doubles. Higher-order filters—such as second-order (12 dB/octave) or fourth-order (24 dB/octave)—attenuate more aggressively.