MENTALS, DEFINITIONS, AND KEY TERMS Analog audio played slower or faster than the speed at which it was recorded, sounds speeded up or slowed down with a directly associated change in pitch. The faster the material is played, the higher the pitch. Conversely, the slower the playback speed, the lower its pitch. Digitized audio can be played SO that speed of delivery and pitch are independently controllable and variable. Digit- ized video can have pixels repeated or skipped in a line and it won't be noticed. Lines in a frame can be repeated or skipped; even skipped or repeated frames are hard to detect, especially if they are skipped or repeated within the context of an undisturbed display scan. Analog content in analog transmission channels or baseband signals on wire are susceptible to myriad distortions and interference. Effects of distortion and interference tend to be incremental and linear. Digital content on the other hand is either resistant to, or immune from interference, or when it fails, it deteriorates rapidly giving rise to a characterization called the cliff effect. In addition to audio and video signals, content may originate in computer systems where it's created by software routines running on hardware. Closed captions appearing at the bottom of a picture are often created by speech-to-text conversion equipment. In any case, and regardless what form the content is in, it's rarely possible to transport it without some further processing, formatting, and multiplexing. Depending on the value of the content, and the number of delivery or reception points, other measures may be required such as encryption, error protection, or replication. Audio Content The concept of how a microphone converts sound waves to electrical energy is simple and well known. Audio signals are derived from microphones. Good sound requires well-behaved, well-placed micro- phones. Connecting the analog output of microphones to a small select group of electronic circuits such as analog-to-digital converters, filtering, processing