The speed of sound is the distance travelled per unit time by a sound wave as it propagates through an elastic medium. In dry air at 20 Â°C (68 Â°F), the speed of sound is 343.2 metres per second (1,126 ft/s; 1,236 km/h; 768 mph; 667 kn), or a kilometre in 2.914 s or a mile in 4.689 s. The speed of sound in an ideal gas depends only on its temperature and composition. The speed has a weak dependence on frequency and pressure in ordinary air, deviating slightly from ideal behavior.
A flute is a musical instrument that produces sound when a stream of air is directed against the edge of a hole, causing the air within the body of the instrument to vibrate. Most flutes are tubular, but some are globular or other shapes.
Flutes have existed since prehistoric times. A fragment of a cave bear thigh bone containing two holes, discovered in Slovenia in 1995, is believed by some scientists to be part of a flute used by Neanderthals more than 43,000 years ago. Flutes were used by the Sumerians and Egyptians thousands of years ago. Some ancient Egyptian flutes have survived, preserved in tombs by the arid desert climate. This Egyptian instrument was a vertical flute, about one yard (0.9 m) long and about 0.5 in (1.3 cm) wide, with between two to six finger holes.