Airplane sound when driving

I have a 2005 Mazda 3 and in the last couple of days my car has been making a sound like a small airplane as I’m driving along. It doesn’t happen when I am accelerating and it quiets down as I slow down. I have no idea what could be wrong…any ideas?

Exhaust system problem?

I’ve had this sound more than once from a tire going flat. Check your air pressures and check back.

Isn’t your car still under warranty? Let the dealership handle it.

How do you know it’s under warranty. With mileage…my warranties usually last less then 2 years…Sometimes one.