The Siren

The siren sounds like a police siren to me.

I think its important as it helps prove the existence of a tunnel or shaft close by.

The microphone is placed in an alleyway that is covered, as such the microphone is best part shielded from the road.

Given that the microphone is always in the same place and the police siren is at a constant volume, would you expect the siren to be the same or different on the recordings?

It is different every time.

The siren does sometimes pass on the road, the noise is of short duration, but in the recordings the noise of the siren can be heard for up to five minutes.

Do you think the following noise is coming from the road?

Please bear in mind that the microphone is inside a 1.5 meter shaft dug in to the basement wall of our house

The position of the shaft is around 10 meters from the road.

The Vietnamese run nail bar Sophia Nails sits between the basement and the road.

Here is a short recording of the siren.