Crest Factor

Crest factor reveals the "peakiness" of a signal — how much headroom is needed between the average level and the peaks. It is the fundamental metric for gain staging, amplifier sizing, and detecting dynamic range processing artifacts. For system design, crest factor determines how much amplifier headroom is needed above the nominal operating level. If a PA system runs at 100 dBSPL average with program material having a 12 dB crest factor, the amplifier must be capable of 112 dBSPL peaks without clipping. Undersized amplifiers produce audible distortion during peaks. Oversized amplifiers waste budget and rack space. Monitoring crest factor during a performance reveals dynamic range compression. An unprocessed music signal typically has a crest factor of 16-20 dB. Heavy limiting reduces this to 6-8 dB. Broadcast audio processing (radio, TV) intentionally reduces crest factor to maximize perceived loudness. In live sound, watching the crest factor helps the engineer balance loudness with dynamics. Crest factor is also a diagnostic for problems. A suddenly low crest factor on a previously dynamic channel may indicate clipping upstream (in the signal chain), feedback onset (a single sustained tone has low crest factor), or a stuck compressor. Conversely, an unusually high crest factor in pink noise could indicate impulsive interference (thumps, clicks) that inflate the peak value. In testing and measurement, crest factor of the test signal must be specified. IEC 61672 requires sound level meters to handle signals with crest factors up to 23 dB for Class 1 and 17 dB for Class 2. SonaVyx computes acoustic crest factor in real time using Rust WASM and displays it in the cross-pollination metrics bar during measurement.