weird ticking sound at higher speed in my Cadillac Seville?

[John Fiddlemits]

I need someone to help steer me into the right direction as to figuring out what this one particular noise could be happening. When ever I travel at higher speeds, at about 60mph, i hear a weird ticking noise, but i NEVER hear it when im parked and idled or even when i rev the engine in park.

does anyone have any idea as to what this could possibly be?

thank you