The guitarist swore on his vintage Marshall that they were a quiet band. 'We never go above 85, man. We're professionals.' The drummer nodded in agreement, which was impressive given his kit had two kick drums and eight toms.

The venue had a noise limiter set to cut power at 96 dBA. The band tripped it during soundcheck. During the first song. During the intro. Before the vocals even came in.

I placed a calibrated measurement mic at the mix position, fifteen meters from the stage. The LAeq over the first three songs was 108.2 dBA. The peak hit 117 dBA during what the guitarist called 'the quiet bit.'

'Your meter must be broken,' the guitarist said. I showed him the display. He squinted at it like a man reading his own parking ticket. 'That's in dBC though, right?' It was not in dBC. 'Well it's the room then. The room's adding volume.' That is not how rooms work.

We eventually negotiated the PA down to 95 dBA at mix, which the band described as 'basically unplugged' and 'an insult to rock and roll.' The audience described it as 'still very, very loud.'

The Moral: Human perception is terrible at estimating absolute levels. SonaVyx's SPL meter with real-time OSHA dose tracking removes the guesswork. At 108 dBA, the audience hit their daily noise dose in about four minutes. Rock and roll is wonderful. Hearing loss is not.