Answer 3—Telephone speech remains understandable at data rates as low as 2,400 bps using modern codecs. This represents a compression ratio of over 20:1.

Most people consider an MP3 file encoded at 128 kbps to be near CD quality. This represents a compression ratio of about 10:1.

Standard-definition digital TV looks pretty good at 6 Mbps, and high-definition signals can be delivered using approximately 20 to 24 Mbps. This represents a compression ratio of about 50:1. Video systems tend to be much more forgiving of high compression ratios than audio systems.

Contributor: David Tweed