The festival license specified 75 dBA at the nearest residential property line, 200 meters from the main stage. The festival sound engineer was measuring 98 dBA at the FOH desk, 40 meters from the PA. 'We're fine,' he announced.

The council noise officer was measuring 83 dBA at the property line. 'You're 8 dB over the limit,' she radioed. The sound engineer looked at his meter, looked at the stage, and made the classic error: 'But it's only 98 here.'

This sparked a two-hour radio argument about inverse square law that nobody won. The engineer argued that sound drops 6 dB per doubling of distance, so 98 dBA at 40 meters should be about 83 dBA at 200 meters. He was right about the math. He was wrong about reality, because inverse square law applies in free field conditions, and a field with 12,000 people, a beer tent, and a Ferris wheel is not exactly an anechoic chamber.

Wind direction, ground absorption, atmospheric conditions, and the beer tent acting as a surprisingly effective reflector all conspired to deliver more energy to the property line than simple math predicted.

The Moral: Noise propagation outdoors is complex. Never assume inverse square law alone will predict boundary levels. Use SonaVyx's environmental noise monitor with Lden/Ldn tracking at both the source and the boundary simultaneously — and measure, don't calculate, because physics has a sense of humor.