Eight decibels quieter, measured badly but consistently
What is measured
Ten minutes at the crossroads at eight on a Tuesday, monthly since 2019. Same phone until it broke, then a calibrated meter.
The change
About eight decibels, which is a substantial reduction. It coincides with the bypass opening in 2022 and the timing is unambiguous.
The caveats
A phone app, one location, and a change of instrument halfway. All three are real problems and all three are smaller than the effect.
