NotesAC

Stringed instruments are characterized by having (you guessed it!) strings
 * Strings**

** How the pitch is changed **
Length, thickness, tension, and density of the string material all affect the pitch of a given string. Longer, thicker, denser, and looser strings all vibrate more slowly than shorter, thinner, less dense, and tighter strings. Slower vibration means lower pitch; faster vibration means higher pitch. The different pitches on most stringed instruments are obtained either by having many strings of different lengths, as on a harp, or by changing the vibrating length of strings by stopping them at different points, as on a violin or guitar. The washtub bass changes pitch by varying string tension

Playing Different Notes
Different notes are produced in different ways by string instruments. Instruments like the zither, harp, and piano have sets of parallel strings, one for each note, that can be sounded individually, or together to make chords. Instruments like the guitar or violin use the fingers to lengthen or shorten the lengths of strings, to produce different pitches. You can try with this imaginary one-stringed, four-fret guitar. Just click on a fret to see how it affects the pitch. =﻿Sound Waves= Sound waves exist as variations of pressure in a medium such as air. They are created by the vibration of an object, which causes the air surrounding it to vibrate. The vibrating air then causes the human eardrum to vibrate, which the brain interprets as sound. Sound waves travel through air in much the same way as water waves travel through water. In fact, since water waves are easy to see and understand, they are often used as an analogy to illustrate how sound waves behave. When a string vibrates, it creates a sound wave. The longer that string is, the longer the sound wave is and the shorter that string is the higher the sound wave. The width of the string also plays a part: thinner is higher, while thicker is lower. On a violin, for examp

** Development of ideas **

le, there are four strings each tuned to a different note based on their width. This gives a violin four basic notes that can be played by either plucking or drawing a bow across the string People have long recognized the difference between high- and low-pitched notes. The great Italian scientist [|Galileo] first put forward the idea that the pitch of a sound was determined by the frequency of its vibrations. This theory was not proved until the 17th century by Robert [|Hooke], who made a wheel which had small teeth sticking out from the edge at equal intervals all round it. He rotated the wheel on an axle and pressed a card onto the teeth so that a sound was given out by the teeth hitting against the card. A similar sound is given out when a ruler is dragged across some railings. If there were 100 teeth on the wheel and the wheel was rotating twice every second, then in one second the card would be hit 200 times by the teeth and the frequency of the sound would be 200 vibrations per second. By increasing the speed at which the wheel was rotated, the frequency would automatically be increased too. Hooke noticed that this increase in speed and frequency gave rise to notes of higher pitch. By doubling the speed the note would be raised one octave. It can, incidentally, also be proved that the irregular frequencies of a wheel with unevenly spaced teeth do not give a note of a certain pitch but only an unmusical noise. Later methods of producing notes of a given pitch worked by blowing compressed air through holes that are evenly spaced round the circumference of a rotating disk. The siren works on this principle.