Overtones help make sounds recognizable. A flute, for instance, has quite a pure sound with most overtones in harmony with the fundamental. A violin has a brighter sound with harsh overtones. Speed of sound Sound travels at different speeds in different substances, and travels faster in warm air than cold air. In pure water, it reaches 1500m per second, and in solid steel it travels at 6000m per second.
Sound waves ripple out in all directions from the sound source, gradually losing energy.
Vibrating string If you look closely at a violin or guitar string, you can see the vibrations that send sound waves through the air. The shorter the string is, the more quickly it vibrates to and fro, making higher-pitched sound. The decibel scale is logarithmic, which means a 2dB sound is ten times as loud as a 1dB sound and a 20dB sound is 100 times as loud.