The advances in digital electronics of the last two decades have resulted in enormous improvement in the recording, reproduction, and distribution of sound. The compact disc and DVD have greatly reduced the noise and distortion that were always present when vinyl records and analog magnetic tape were the main distribution media. However, audio is not yet perfect—far from it. The weak links in the audio chain now are the transducers that convert sound from pressure waves in the air to electrical signals or vice versa. Among the transducers, the most problematical are the loudspeakers.