<P> It is sometimes said that the sounding board or soundbox "amplifies" the sound of the strings . Technically speaking, no amplification occurs, because all of the energy to produce sound comes from the vibrating string . What really happens is that the sounding board of the instrument provides a larger surface area to create sound waves than that of the string . A larger vibrating surface moves more air, hence produces a louder sound . </P> <P> All lute type instruments traditionally have a bridge, which holds the string at the proper action height from the fret / finger board at one end of the strings . On acoustic instruments, the bridge performs an equally important function of transmitting string energy into the "sound box" of the instrument, thereby increasing the sound volume . The specific design, and materials the used in the construction of the bridge of an instrument, have a dramatic impact upon both the sound and responsiveness of the instrument . </P> <P> Achieving a tonal characteristic that is effective and pleasing to the player's and listener's ear is something of an art and craft, as well as a science, and the makers of string instruments often seek very high quality woods to this end, particularly spruce (chosen for its lightness, strength and flexibility) and maple (a very hard wood). Spruce is used for the sounding boards of instruments from the violin to the piano . Instruments such as the banjo use a drum, covered in natural or synthetic skin as their soundboard . </P> <P> Acoustic instruments can also be made out of artificial materials, such as carbon fiber and fiberglass (particularly the larger, lower - pitched instruments, such as cellos and basses). </P>

All string instruments are played with a bow