nanog mailing list archives
Re: Cellphones and Audio (was Ghost Click, though I got no idea why)
From: Jay Ashworth <jra () baylink com>
Date: Thu, 3 May 2012 11:01:01 -0400 (EDT)
----- Original Message -----
From: "Adam Atkinson" <ghira () mistral co uk>
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?
No, you weren't. A 4khz channel is generally good from 3-400hz up to about 3.4khz, and if you look at spectrograms of the various categories of voices you can see the differences, though they're not always as clear cut as you might expect: http://www.dplay.com/tutorial/bands/index.html In general, though, intelligibility comes from the higher frequencies, and 3.4kHz is *usually* high enough. What might be the case is that you'd have more trouble *distinguishing* amongst women, or between women and children, because the tones necessary for that are more located above the cutoff frequency. In short: it depends a lot on what you mean by 'serves well'. :-) Cheers, -- jra -- Jay R. Ashworth Baylink jra () baylink com Designer The Things I Think RFC 2100 Ashworth & Associates http://baylink.pitas.com 2000 Land Rover DII St Petersburg FL USA http://photo.imageinc.us +1 727 647 1274
Current thread:
- Re: Operation Ghost Click, (continued)
- Re: Operation Ghost Click Jeroen van Aart (May 02)
- Re: Operation Ghost Click Christopher Morrow (May 02)
- RE: Operation Ghost Click Eric Wieling (May 02)
- Re: Operation Ghost Click Sean Harlow (May 02)
- Re: Operation Ghost Click Jeroen van Aart (May 02)
- Re: Operation Ghost Click Valdis . Kletnieks (May 02)
- Re: Operation Ghost Click Joe Hamelin (May 02)
- Cellphones and Audio (was Ghost Click, though I got no idea why) Jay Ashworth (May 02)
- Re: Cellphones and Audio (was Ghost Click, though I got no idea why) Adam Atkinson (May 02)
- Re: Cellphones and Audio (was Ghost Click, though I got no idea why) Robert Bonomi (May 03)
- Re: Cellphones and Audio (was Ghost Click, though I got no idea why) Jay Ashworth (May 03)
- Re: Cellphones and Audio (was Ghost Click, though I got no idea why) Valdis . Kletnieks (May 03)
- RE: Cellphones and Audio (was Ghost Click, though I got no idea why) Brandt, Ralph (May 03)
- RE: Cellphones and Audio (was Ghost Click, though I got no idea why) Brandt, Ralph (May 03)
- Re: Cellphones and Audio (was Ghost Click, though I got no idea why) Adam Atkinson (May 03)
- Re: Cellphones and Audio (was Ghost Click, though I got no idea why) Jay Ashworth (May 03)
- Re: Cellphones and Audio (was Ghost Click, though I got no idea why) Joel jaeggli (May 03)
- VoIP/Mobile Codecs (was Re: Operation Ghost Click) Sean Harlow (May 02)
- Re: VoIP/Mobile Codecs (was Re: Operation Ghost Click) Jeroen van Aart (May 02)
- RE: VoIP/Mobile Codecs (was Re: Operation Ghost Click) Brandt, Ralph (May 03)
- VoIP vs POTS (was Re: Operation Ghost Click) Jared Mauch (May 02)