In 1914 Erich von Hornbostel and Curt Sachs published a system for sorting instruments by how they make sound.
Sound waves change with the air they travel through. The speed of sound in air increases with the temperature of the air. The higher the frequency of a sound, the smaller its wavelength. All resonant frequencies are whole-number multiples of the fundamental, and together they are called harmonics. Sounds above 20,000 hertz are called ultrasound, and sounds below 20 hertz infrasound. By convention the note A4 is often set at 440 hertz.
On a violin the bridge transfers some of the string's vibration energy to the body, and the body pushes air because it has a large surface area. The oldest documented violin with four strings was made in 1555 by Andrea Amati, and in 1560 French king Charles IX ordered 24 violins from him. In a double-blind test of 21 professional violinists playing six violins, only 8 of the 21 chose an old violin to take home. Electromagnetic pickups on an electric guitar change the vibration of the steel strings into electrical signals.
A woodwind has a long, thin column of air. The lowest note is played with all the tone holes closed, when the column is longest. Reeds are made of springy cane and can vibrate on their own. The clarinet is credited to German maker Johann Christoph Denner and grew from an older instrument called the chalumeau. A bugle has a fixed length of tube and can produce only a limited range of notes. Trumpets date back to 1500 BCE and earlier, and Tutankhamun's tomb held bronze and silver trumpets.
A drum has a drumhead, a body, and a way of attaching the head to the body. Like a string, a drumhead gives a higher pitch when its tension goes up. A snare drum has screws on the rim to adjust the tension. Drums make sound when they are hit, shaken or scraped, and they belong to the percussion family. A piano is counted with the percussion family too, because it makes sound when hammers strike its strings.
Bartolomeo Cristofori, who worked for the Medici family in Florence, Italy, built the first piano in the early 1700s. A harpsichord's notes came when a plectrum made from a bird's quill or leather struck the string. The harpsichord plucked its strings and could not change how loud a note was. Cristofori made a harpsichord that can play quietly and loudly, and the name was soon shortened to pianoforte. He built only about twenty pianos before he died in 1731. Almost every modern piano has 88 keys.
One of the oldest flutes was made from the naturally hollow wing bone of a griffon vulture, with five finger holes and a V-shaped mouthpiece. Its pieces were found in 2008 at Hohle Fels, a Stone Age cave in southern Germany. Mammoth-ivory flutes were hard to make: with only stone tools, the maker split curved ivory along its grain, hollowed out the two halves, carved them and fitted them together with an airtight seal. In China, Jiahu's bone flutes are between 7,000 and 9,000 years old, and fragments of about 30 other flutes were also found there.
Some instruments are much newer. Robert Moog's 1964 paper described the foundation for a voltage controlled oscillator, which many later synthesizers built on. Steel pans began in Trinidad and Tobago in the late 1930s, and the main object used to make them was a 55-gallon oil drum. In 1945 the first fourteen-note steel pan with chromatic tones was developed.
Most noise-induced hearing loss comes from damage and death of hair cells in the ear, and human hair cells do not grow back. The louder the sound, the shorter the time it takes for hearing loss to happen. 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.
Words to know
- harmonics: overtone family
- pickups: guitar sensors
- fundamental: lowest frequency
- wavelength: wave size
