HOW LOUD IS YOUR WHEELIE BIN !!!!!

Noticed this when I was putting the rubbish out.
Db - Decibels - level of sound / noise.
What on earth would something like this be on a wheelie bin for?
The thing is, it must have been testsed in order to be slapped with an 89Db sticker.
How did they do it?
Trundled it up and down while a wee manny recorded the noise level?
Filled it up with rubbish, left it for 2 weeks, and measured how loudly it HUMMMMED?

What will be measured and stickered next then?
Popcorn sold in cinemas?
Squeaky doors in libraries?
Pews in churches?

Discuss.

JimH.