A high pitch noise when runing on 40mi~70mi and accelerating

The noise is coming from front side, and according to the speed range, it looks like it only happen when the third gear is used (automatic transmission). Another person also tell me it sounds like a gear noise.

Well, at lower speed like 40mi, it sounds like some wind going through a tunnel. But when speed goes up, the pitch of the noise increase and finally becomes something very annoying, like some high-pitch noise coming from a FM radio.

The noise only appears when the I step on the gas peddle.

I guess there's something wrong with the transmission. But not sure what I can do to fix it, and how much I need to pay. I saw a mechanic guy but he also cannot tell the exact reason.

Can anyone having the experience tell me the truth?

thanks. Does this noise sound like it is coming out of the radio speakers? Sometimes you can get interference from the alternator and it will produce a noise like you describe, coming from the speakers.Car Repair Talk's forum.