So as I was driving yesterday i noticed that there was a noise that sounded much like a honda exhaust with a fart can on the back of it. It is there when you punch on the car and it is there at idle as well. it just popped up and when idling in the driveway it is a low flat sort of tone, that increases in repetition as the engine rpms increase. I opened the hood and it is fairly hard to hear from the engine compartment. However it is very noticeable from the middle section of the car. Possibly something to do with the exhaust? Any ideas about how i should approach this? Or if this has happened to anyone before?

 

u probably have a hole in your exaust