Compact disks

Speech and music are stored on compact disks (CDs). This medium gives several advantages over magnetic tape. Some CDs can store video data.The basic asset of CDs is their superior reproduction quality. All the problems associated with the older vinyl disks can be eliminated. There is no limit to the times a CD can be replayed, as the laser beams are used to recover sound. The lasers bounce off small pits on the disk. Light beams, do not scratch the CD; nothing mechanically rubs against disk. A CD will not jam because it does not move while it is getting replayed. The data cannot be distorted by stretching, as can happen with the magnetic tape.

Modern CD recording devices digitize speech or music. This results in infinite reproducibility, as digital highs and lows are unmistakable and do not get distorted. A multigeneration reproduction sounds every bit as good as a 1st-generation reproduction. Of course, there’s a limit to how many digital reproductions can be made without error; no system is perfect. A 500th-generation digital recording may have a few errors, where stray noise pulses have mutated l’s into 0’s or vice-versa. But the 500th-generation analog reproduction would consist of indecipherable hash.