My car started making whistling noises recently. I first noticed when I was inside the car on idle for around 15minutes while I was cleaning the dashboard. Then I started hearing a strange noise which changed to a low whistling sound then get louder and louder - it sounds like a tea pot kettle when it’s ready.

I followed the noise and found that it was coming from under the car a bit a the back maybe between the back tires. My initial thoughts are it could be a leaking hose? Because it sounds like air excaping from a tiny hole from a tire but it’s not coming from the tires and the sound only starts when the engine is on.

I tried opening all the doors maybe it’s a door seal leak but nope. I tried turning the ac on and off but still no change. It also happen when I switch the car on (turning the key ready for starting).

Anyone encountered this issue before?

Here’s a video of the noise:

 

Don't have any definite explanation at this time.
If you just urn the key on without starting the engine, is it possible for you or someone to get under the vehicle and possibly determine just where the sound is loudest?