An idiophone is any musical instrument which creates sound primarily by way of the instrument's vibrating, without the use of strings or membranes.
The vibraphone is similar in appearance to the xylophone, marimba and glockenspiel. Each bar is paired with a resonator tube having a motor-driven butterfly valve at its upper end, mounted on a common shaft, which produces a tremolo or vibrato effect while spinning. The vibraphone also has a sustain pedal similar to that used on a piano; when the pedal is up, the bars are all damped and the sound of each bar is shortened; with the pedal down, they will sound for several seconds.
A xylophone is a musical instrument in the percussion family that consists of wooden (not steel) bars struck by mallets. Each bar is an idiophone tuned to a pitch of a musical scale, whether pentatonic or heptatonic in the case of many African and Asian instruments, diatonic in many western children's instruments, or chromatic for orchestral use. The term may be used generally, to include all such instruments, such as the marimba and balafon or, more specifically, to refer to an orchestral instrument of somewhat higher pitch range than the chromatic marimba. It is sometimes mistakenly used of similar lithophones and metallophone instruments of the glockenspiel type such as the pixiphone.
A pentatonic scale is a musical scale with five notes per octave in contrast to a heptatonic (seven note) scale such as the major scale and minor scale.
