Adam Atkinson <ghira@mistral.co.uk> wrote;
Jay Ashworth wrote:
Now, those codecs *are* specially tuned for spoken word -- if you try to stuff music down them, it's not gonna work very well at all...
It was claimed to me many years ago that the 4kHz cutoff used in POTS serves women and children less well than it does adult males. I have never been aware that I have any greater problems understanding women or children on the phone than I do men, but my hearing is not great. I can't hear the difference between G.711 and G.729, for example, but some people can.
Googling "PCM adult male voice", "4kHz adult male" and similar isn't finding me anything. Was I told nonsense?
Probably. "sort of." <grin> 'Way back when', at least in the U.S., the 'voice' passband was 300-3000Hz. Later, 300-3300Hz. For perspective, rf you know anything about music, the 'A' below "Middle C' is nominally 440Hz. 300Hz is roughly an octave below Middle C, and 3kHz is 2-1/2 octaves above it. That's the -high- end of the range for a piccolo, or coloratura Soprano. Now, absent the overtones that give a note it's 'color', one of those high-pitch sources will sound more than a little bit 'tinny' over a classical 'voice passband' channel. *HOWEVER*, the 'fundamental' frequencies for womens/childrens voices -is- higher than that of adult males. But you're talking less than an octave in 'most' cases. Less than 2 in 'extreme' (a guy with a _deep- bass voice -- "basso profundo", and a 'squeaky' female/child) cases. This mean that one does lose one to two additional 'overtones' of the fundamental on women/children, vs. men. This does, in general, *NOT* materially affect the 'intelligibility' of the voice, although it does have a measurable adverse effect on the 'identifiability' of one such higher-pitched voice vis-a-vis a different similarly-pitched voice. You lose more of the 'color' of their voices vs the lower-pitched male voice.