Assalamu Alaikum,
There are some theories about this. Some scientists say that human “perception of the environment” may be influenced after a UFO sighting or even an alien abduction. That may explain sounds that were heard at Stonefield Beach, Oregon after a "UFO sighting".
Strange sounds heard in Kiev may be explained by its place in nature: "In Lieder's version, taken from her Aug. 21 newsletter, her source, the Zetas, give this explanation: Kiev lies just south of a dam on the Kiev Reservoir, a damming of the Dnieper River. A vibration of the dam itself, like the strings of a violin, would resonate in the water, thus not only creating a vibration in the ground but a vibration in the air. There are musical instruments that use a water filled container to increase the vibration, so the vibration affects the air and send a tone forth. Glasses of water filled to different heights, when tapped, create a vibrating tone due to the water surface affecting the air. The glass alone, when tapped, is barely audible. Where trumpets will be heard, worldwide, prior to the pole shift, the Kiev trumpets are not due to upper atmosphere clapping caused by lightning. They are caused by the stretch zone above the Black Sea, which will be pulling apart continuously until the hour of the pole shift. Thus, the people of Kiev should become accustomed to the music their dam is producing, as it is likely to be with them for the duration."
Sources: htt p: // w ww. huliq. co m/ 10282/ ufo- sightin gs- str ange -sounds- worldwide- while- radium -called- alien- gift
http: //jlnavarro.blogspot.com/2011/08/two-explanations-of-strange-sounds-in. html
(Copy and Paste, then take away the spaces)
Sorry, I have less than 15 post so I can't post links.
Of course, these are just theories. Allah knows best.