But the judge needs to know if the noise was just a nuisance or legally unacceptable, so the noise needs to be monitored. Some authorities have permanent noise monitors in place, like this one near Sydney airport.

The microphones's measurements have to be absolutely correct. And Australia's science agency CSIRO makes sure that they are.

The microphone is placed in what is called an anechoic chamber or echo free chamber then subjected to a series of sounds.

When we're testing this device we need to have sounds which are coming from one direction only and it's coming from the source towards this microphone and the microphone is picking it up.

The sounds begin at a very low frequency, before increasing to a glass shattering pitch above most hearing.

The importance of what we are doing, is to reassure the customers, in this case the airport sound monitoring authority, that the microphones that they're using BUT respond correctly to all frequencies. That they are not faulty and that they're performance is adequate to their specifications.

It won't stop the noise… but it does provide a sound basis to help manage an increasingly noisier world.