1997 Mazda Miata MX-5

I'm not very car saavy, but my father is. He does most of the repairs on my car. For the past few months, though, there has been a loud noise coming from the rear somewhere. We don't know what it is. It is always there, but the noise increases with speed. It's very consistent in that it always sounds the same. It seems have something to do wth every time the wheel goes around. The faster the wheels turn, the louder and faster the noise gets. It sounds like a low pitch hum that goes up and down as the wheel turns. It's very annoying as it makes it difficult to talk to my passangers and is particularly bad because of the thin vinyl convertible top. Do you have any advice as to what we should be looking at/for?

Also, the right, rear wheel squeaks about 75% of the time. The brake pads were replaced a month ago, and are broken in by now, but just in case something was stcuk on it, we cleaned the pad. The wheel squeaks, though, when it is turning, not when the brake is applied. From reading your other forum comments, my guess is its a bad wheel bearing. Thanks for your time!