A musical instrument is an item modified or constructed with the purpose of making music. In principle, anything that produces sound somehow, can serve as a musical intrument, but the expression is reserved generally to items that have that specific purpose.
Instruments are often divided by the way in which they generate sound.
- Wind instruments generate a sound when a column of air is made to vibrate inside them. The frequency of the wave generated is related with the length of the column of air, so this instruments can produce specific tones. Different methods for varying the length of the column of air exist for example: holes in flutes, clarinets or similar, actually varying the length in the trombone, keys that lead to differents paths for the air in the trumpet, organ, horn, etc.
- Percussion instruments that create tones when hit by creating vibrations in the body of the instrument. Examples are various drums, xylophone, castanets.
- String instruments generate a sound when the string is plucked, strummed, slapped, etc. The frequency of the wave generated (and therefore the tone produced) usually depends on the tuning (tension) of each string, as well as the length of the string controlled by the position of the player's finger, pressing it against the neck of the instrument. One exception to this rule is the harp, which has no neck for the strings to be pressed against; each string will therefore produce only one tone according to how it is tuned.
- Voice, that is, the human voice, is generally also considered to be a Musical instrument. Voiced sounds are generated by airflow from the lungs setting the vocal cords into oscillation. The fundamental frequency is controlled by the tension of the vocal cords and the spectral envelope by the formation of the vocal tract. Many other sound types are also possible.
- Electronic instruments generate sound through electronic means. They often mimic other instruments in their design, particularly keyboards.
- Keyboard instruments are wind instruments (organ), string instruments (harpsichord, piano) or electronic instruments (synthesizer) that are played by a keyboard. Every key generates a single tone. Most instruments do have extra means (pedals for a piano, stops for an organ) to manipulate that tone.
Further subdivisions (and different ones) are possible.
Most likely the first instruments were percussion instruments, maybe a hollow trunk, or stones hit together, that are useful to create rhythm, but not always melody. But all classes of instruments have a long history, being mentioned in various ancient sources: egyptian inscriptions, the Bible, ....., etc.
- Wind or air based
- Keyboard Based
- Electronic / Synthesizer