this really has the aroma and flavor of our beloved CHICAGO written all over it. for the moment i'll assume it's legit and suggest you try the below. crap shoot as you failed to mention mileage...any recent glitches or problems right before this episode...how much oil you added....failure to describe the "sound" you heard....failure to mention the location of the air being "released"....failure to mention an active "trouble code warning light"....failure to mention whether or not oil pressure warning light was activated.
1-you need to establish a starting point----a baseline if you will. park bike on side stand....remove swingarm drain plug....drain oil...remove factory lower cowling (7 screws)...remove oil filter. let filter mount and swingarm drain for at least 1/2 hour.
2-install new filter....install drain plug with new O-ring on it....install EXACTLY 2-1/2 QUARTS of correct type and viscosity oil....install cowling....now start and check that your dashboard oil pressure warning light extinguishes. if so ride it gently and see what you now have.
3-if your dashboard oil pressure light does NOT extinguish shut off motor....remove swingarm fill cap/dipstick assembly and restart motor letting it idle at 1000rpm. this method "burps" an air-bound oiling system. if oil pressure light stays on after approx. 20-30 seconds then immediately shut off motor and do NOT start it again. you have a serious problem that will need tended to by a qualified buell/sportster tech.