All sound comes from vibrations. A vibration is a movement that starts when something is disturbed. The faster something vibrates, the higher the pitch. Pitch is how high or low a sound is. People can hear sounds from about 20 to 20,000 hertz. Listening for a long time to sounds at or above 85 decibels can damage hearing. Extremely loud noises can damage hearing too, and wearing earplugs in loud places helps protect it.
A string on its own makes little sound, because it is thin and slips easily through the air. A string instrument is made of wood. Its strings vibrate to make the sound. The hollow body pushes the air and makes the sound louder. A harp's strings are played by plucking them with the fingers. A violin is played with a bow. A bow is a stick with a ribbon of horsehair. An electric guitar makes little sound unless it is plugged into an amplifier.
Most woodwinds have a reed, a small piece of cane or wood that shakes when air goes across it. A clarinet has a single reed made from the cane of a type of grass. Air makes the reed vibrate, and that makes the sound. The clarinet and saxophone use one reed, while the oboe and bassoon use two. A flute has no reed. Its sound comes from air that hits an edge, making the air in the tube shake.
A flute or oboe player changes the note by opening and closing finger holes. That changes the length of the column of air. In a wind instrument, a longer tube makes a lower note. So a tuba needs a tube so long that it is coiled into loops. A piccolo is a small flute that plays very high notes. Brass players make sound by buzzing their lips into a metal mouthpiece.
Percussion instruments, such as drums, make sound when they are hit, shaken or scraped. A piano makes sound when felt hammers strike its metal strings. So it is counted with the percussion family. Bartolomeo Cristofori worked for the Medici family in Florence, Italy. In the early 1700s he built the first piano. An orchestra has four groups of instruments: strings, woodwinds, brass and percussion. The principal first violin in an orchestra is called the concertmaster. A conductor usually leads an orchestra. The conductor directs the music with gestures you can see.
Flutes made from bone and ivory, found in caves in Germany, are among the oldest known musical instruments. They are about 40,000 years old. In Jiahu, China, archaeologists found bone flutes between 7,000 and 9,000 years old, made from the wing bones of big birds. They have five to eight finger holes. The best-preserved one has been played. A flute has no reed. Its sound comes from air blown against an edge.
Words to know
- vibration: fast shake
- pitch: how high
- reed: thin cane
- conductor: orchestra leader
- percussion: hit instruments
