text: Strings have sound because they vibrate in harmonic waves.  The length of those waves, or "wavelengths" is one factor that affects how the sound will behave.\n\nSince both ends of the string are fixed tight, the waves are forced to begin and end in a definite space.  This forces the wavelengths into lengths that are dependant on one wave starting and finishing from one end of the string to the other.  Since different string lengths will produce different wavelengths, the sound will behave differently.  \n\nThe other main factor that affects sound is tension.  The tighter the string, the shorter the wave will be.  A short wave height, or "amplitude" causes the wave to move faster, which produces a higher pitch.\n\nSo, you have wavelength and amplitude.  Those two things could take up a whole semester of physics, but they're relatively simple concepts.  (Unless you play trumpet)