Can you tell me what this is cause the auto shop is trying to play me

What is your question?

Lately I been driving my car I been hearing this sound over the engine. It sounds like a huge vacuum vooooooooom sound kind of loud inside the car it comes on once I reach 35-40 mph. When I slow down it slows down too. Took it to the shop with the warranty they fix everything but this. Took it back the next day they said it's bad tires and tried to sell me tires. The ones they said was bad was switched to the rear. To me the sound is coming from the front they say it's the back. I'm thinking transmission. Have you ever heard anything like this before and know what it is.