Fast moving object with cyclic whistling noise.On the corner of Sherwood Dr and Seacrest Dr in Largo, FL, zipcode 33771.My wife and I were walking at about 8:00 pm, when I heard a strange noise coming from the Southwest. It sounded at first like a car with a bad axle or something, with a repeating whistling noise I could only describe as “whoo-whoo-whoo-whoo”, only very highpitched.The noise got closer, but since there were no cars or anything else obvious we stopped to see where it was, and then could hear as it passed overhead. Based on the volume, it seemed close to us, and even made a “Doppler Effect” as it passed by. There were clouds so I couldn’t see it, but I did see what appeared to be a shadow on the clouds, as if something was passing by over them. The shadow was somewhat oval shaped, almost cigar shaped, but was moving “sideways”. The shadow could be seen in two spots at once, but I cannot describe what I mean.It moved quickly, too fast for a helicopter at that height, and was gone within a few seconds.