Scientist Ralph Bagnold told that during his stay in the desert suddenly heard lasting for a few minutes the sound of low intensity, so piercing, that human speech drowned. This sound usually appeared in the quiet evenings following a windy day.
It was not a sound nor carried by animals or by humans or some extraordinary machine. He came from the dunes, which sang. It is known that the sands of the southern Sahara desert of Takla Makan and central Asia and in the Rub al-Chali in Saudi Arabia appear to these strange and often frightening sounds.
Sand is composed of quartz particles. When the sand has the same size are set in motion by the wind or by passing an animal, they start small waves roll through the slopes of the dunes, like oil on glass. Sometimes during the rolling sand can be heard vibrating groan, which turns into a rumble, dying when the waves of sand, motionless.
It seems that temperature plays an important role in the process of singing – the more heated is the top layer of sand, the louder sounds.