bonomi at mail
May 3, 2012, 1:29 AM
Post #3 of 10
Adam Atkinson <ghira [at] mistral> wrote;
Re: Cellphones and Audio (was Ghost Click, though I got no idea why)
[In reply to]
> 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.
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.