The most striking disadvantage of sound waves are that speed of sound waves are reliant on the density of its medium (more dense = higher speed), and the quality of sound waves may be affected by disturbances in its surroundings. It loses energy as it travels (that's why sound is not easily heard over great distances), and can be cancelled out by higher energy waves (think about a soft voice being drowned out by loud music). Hence sound waves are not reliable modes of information transfer and have been replaced by electromagnetic waves.