From the book pile: the graphic above and quote below are from Future Developments in Telecommunications, 2nd edition by James Martin, 1977 (“NEW completely rewritten”).
A given piece of information is conveyed to humans, sometimes using a low transmission capacity and sometimes a large capacity.
If we watch five minutes of a television talk show a message may be conveyed to us. To transit television digitally (with PCM encoding) requires 92.5 million bits per second. The five minutes therefore take 5 x 60 x 92.5 million = 27.5 Billion bits. More compact signal encoding can reduce this somewhat.
The same message may be conveyed in speech in five minutes of conversation over a telephone line. If the line is digital (PCM), operating at 56,00 bits per second, this uses 5x 60 x 56,000 = 16.8 million bits. In fact it uses twice this because a typical PCM telephone transmits in both directions together so that the parties can both talk or hear each other.
Human conversation is highly redundant, and if the person with the message to convey had been better organized he might have spoken it in 120 words, taking one minute. This would have needed 3.36 million bits.
The 120 words could have been sent by data transmission. Using the coding that is typical today, this would need 4800 bits. If a tighter code had been used (5-bit Baudot code instead of 8-bit ASCII) 3000 bits would have sufficed. If message compaction techniques had been used, the message could have been sent in less than 1000 bits.
Apologies for the title of this post.