Unknown sound of fast and low origin witnessed by three individuals.Two of my brothers and myself were sitting on a "jetty" about 50 feet into the water of the lake (Clear Lake) in a rural setting in Beaver county (the third county East of the shared border with New Mexico). The lake is off the paved roads, rather rural, no electricity or water or sanitary facilities. It sets in a depression surrounded by low rolling hills. We were all fishing, facing three different directions. Suddenly we heard a sound of something traveling at a high rate of speed from the (approximate)ESE. We all looked up when it was at its loudest, apparently directly overhead, and tried to follow the sound as it disappeared in the (approximate) WNW. The entire incident was only about 30-40 seconds. The sound got louder and higher in pitch as it approached us, being loudest and the highest pitch when seemingly overhead, and then got softer and lower in pitch as it disappeared. There was NO odor, color, turbulance (that we could tell), exhaust trail, engine flame, lights, reflection of sunlight... absolutely NOTHING except the sound... a "whooshing" sound of something apparently not extremely large, but moving very rapidly. The few birds there were did not exhibit any unusual behavior, and as nearly as we could tell we were "alone" at the lake. None of us had any idea as to what caused the sound, or the significance of it, or anything about it, except for agreeing to what is reported above. I am a retired school teacher/librarian, age 64, my oldest brother is 69 and a semi-retired printer, my younger brother works for a petroleum company and is 59. We come from different locations... two from seperate locations in the Texas panhandle, one from a small town in the Oklahoma panhandle (different county, however). The weather was fairly calm, sunny to partly cloudy, and warm. The nearest air bases, to my knowledge, are at Clovis, NM, OKC, Altus, OK -- all at some distance from the incident. Educationally, I have two batchelor degrees and a masters; my older brother has a bachelors degree; my younger brother a GED and all of us considerable education from "hard knocks!" I would agree to follow-up contact via e-mail or otherwise (but at no additional expense to us, please).((NUFORC Note: We have located the town of Clear Lake, OK, but the only nearby bodies of water we can locate through www.mapquest.com are Lake Evan Chambers, to the northeast of that town, and