a character or symbol used to represent a sound, esp. one used in phonography.-an instrument for the mechanical registration and reproduction of audible sounds, as articulate speech, etc. it consists of a rotating cylinder or disk covered with some material easily indented, as tinfoil, wax, paraffin, etc., above which is a thin plate carrying a stylus. as the plate vibrates under the influence of a sound, the stylus makes minute indentations or undulations in the soft material, and these, when the cylinder or disk is again turned, set the plate in vibration, and reproduce the sound.