High pitched noise at 100 mph?

I drive a 2001 honda accord and I was driving with my window down and the sun roof open and when I hit about 100 mph I heard this loud very high pitched whistling noise, It sounded like the sound a fastrak makes when pass by a toll station, almost like a beep. I don't think it was the engine, I'm guessing it could've been wind noise because it only does it at high speeds, but I am by no means a car expert so what could it be. I also have a side question, does a 2001 honda accord automatic transmission have a rev limiter? Like is it impossible to red line it?

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