On Nov 4, 12:50 pm, VWWall <vw...@large.invalid> wrote: > k...@kymhorsell.com wrote: > > In sci.math Robert Wessel <robertwess...@yahoo.com> wrote: > > ... > >> Consider that high keystroke rates pretty much require chords, and a > >> chord is most certainly not three or four random keys, pressed at > >> different times and forces - rather they're a small subset of the > >> possible combinations of keys within a hand-span (or two hand-spans in > >> some cases), hit at the same time, and with the same force (in fact > >> there are less than about 10,000 chords). And just like English, you > >> can't really have random sequences, or you'd just have noise. > > >> Still, 40bps intuitively feels a bit light, but not by that much. I > >> expect that if Shannon said something like that, he was considering > >> music to be more along the lines of a MIDI stream than a digitized > >> sound file. > > ... > > > Perhaps we could use spoken language as a guide to the auditory bidrate > > we've evolved to process. As Shannon estimated, each letter in English > > has only a couple bits of entropy, with normal reading speed (that > > uses the auditory processing -- the reason you can't count the number > > of words in a limerick without using your fingers) around 150 wpm. > > Let's call that 25 bps. > > > 40 bps is then about the "square" (in log terms :) of our evolved language > > processing speeds. > > > Maybe not such a bad estimate. > > > The same disparity is then seen between normal good voice compression > > and the actually bitrate we operate on. I.e. 25 bps "back-end" processing > > speed, yet voice compression being still 1000s of bps. > > > In some applications over the years I've used speach-to-text and text-to-speach > > over very low speed lines as a slap-dash compression method. With a bit > > of a phoneme "nomenclator" it wasn't too bad. No doubt the idea is still in > > use, but I don't think I've heard of it in preference to straight dsp methods. > > At the 1939 World Fair in New York City, Bell Telephone had an exhibit > featuring the "vocoder". An operator could synchronize speech by > pressing "keys" on a console. Bell thought the method could be used for > "compressing" its telephone bandwidth requirements. > > As it turned out, bandwidth was not the limiting factor in future > telephone growth. Simple system changes like separating the low-speed > "housekeeping" functions from the in-band "information" were implemented.
The cranks that work in signal processing are bandwidth obessed with all technology, so that's where digital signal processing, Turing Machines, Lasers, Holograms, miniature atomic clocks, Integrated Circuits, XML, Optical Networks, USB, LEDS, Flash Memory, Orbital Solar Energy, and post New York Times ergonomics all came from.
> I was involved in the testing of microwave frequencies in small circular > wave-guide to allow for much wider band channels. The need never > evolved, and fiber optics replaced microwaves where it was needed. > > As far as I know, any "compression" system requires some means of > "storing" information so that it can be processed. This was just being > developed during Shannon's time. It's obvious that "digital" storage is > easier and more flexible than analog. > > -- > Virg Wall