Tony's SPL meter had a calibration sticker on it. It said 'Calibrated: June 2021.' It was now March 2026. The sticker also had a coffee ring on it, which Tony said was unrelated. The corner of the meter was cracked, which Tony said was 'cosmetic.' The battery compartment was held shut with gaffer tape, which Tony said was 'an upgrade.'

Tony had been the noise enforcement officer for the local council for four years. During that time, he had approved noise levels at eighteen venues, twelve festivals, and approximately two hundred events. His meter had been reading 12 dB low the entire time.

Every event he measured at '93 dBA' was actually 105 dBA. Every venue he certified as 'compliant at 96 dBA' was pumping out 108 dBA. He had, through the medium of a dropped and never-recalibrated instrument, inadvertently exposed hundreds of thousands of audience members to noise levels that exceeded every occupational standard by a generous margin.

The error was discovered when a touring engineer's calibrated Class 1 meter disagreed with Tony's reading by a consistent 12 dB across four venues. Tony's meter had a damaged capsule — likely from the drop that also cracked the case — and the sensitivity had shifted permanently.

The Moral: Calibration isn't a one-time event — it's a maintenance program. SonaVyx's SPL meter with 94 dB calibrator support and per-frequency correction curves helps you verify your measurement chain before every session. A miscalibrated meter isn't just wrong — it's dangerous.