260	2006-12-24 12:20:57	ka3j12	Voice Power Spectrum Density
Message	Date	From	Subject
Hi - I've been searching for a graph showing power versus frequency for a typical male and female voice. No luck. I recall hearing somewhere that for the male voice, although the fundamental frequencies are pretty low, most of the power is in the harmonics and/or in the nonvoiced higher frequency (sibilant) consonants. Is that correct? I'm interested in this because simple crystal filters don't offer as much suppression at lower frequencies and I was wondering or hoping that it didn't make quite as much difference due to the power spectrum of the voice. Thanks for your help. Happy holidays everyone! 73, Ron (KA3J)
269	2006-12-24 21:36:07	Rick	Re: Voice Power Spectrum Density
Hi Ron, Interesting question, and no simple answer. The power spectral density of a male radio announcer is different than a man in normal conversation. The power spectrum desired for maximum intelligibility is not the same as for natural sounding speech. There are many resources on the web. Here is an instructive one: http://www.prosoundweb.com/install/commentary/jbl/chptr.php Also, the long-term average spectrum isn't the whole story. Transmitter power, efficiency, and spectral purity off-channel factor into the discussion along with intelligibility and natural sound. Experiments are in order--but as a benchmark, the late 1950's Collins S-line SSB transmitters sound good on the air with male voices, and that system has been described in detail in many publications and handbooks. I believe it's just a modestly flat, 6th order filter with a relatively narrow bandpass (nominal 2.1 kHz) and placement of the carrier 20 dB down the filter skirt. Best Regards, Rick kk7b
271	2006-12-25 05:32:37	w4zcb77	Re: Voice Power Spectrum Density

272	2006-12-25 15:02:00	Lasse	Re: Voice Power Spectrum Density
Ron, I might have one graph buried in a 25 year old stack of paper... did some work way back at the salt mine. You have to QRX a few days until it opens again :) As for intelligibility vs. power most power is in the low end but the high part is absolutely vital for understanding. That is why you often find that speech processors do amplify high frequency, and even try to reduce low end of the spectra. Listening on a pile up, those who cut through is often very high pitched and sounds awful, but, you are able to pick up the call sign. But it is not something to be used for round table chats on 80 m ! Cheers Lasse SM5GLC On Sun, 24 Dec 2006 20:20:31 -0000 "ka3j12" wrote: > Hi - I've been searching for a graph showing power >versus frequency for > a typical male and female voice. No luck. I recall >hearing somewhere > that for the male voice, although the fundamental >frequencies are > pretty low, most of the power is in the harmonics and/or >in the > nonvoiced higher frequency (sibilant) consonants. Is >that correct? > I'm interested in this because simple crystal filters >don't offer as > much suppression at lower frequencies and I was >wondering or hoping > that it didn't make quite as much difference due to the >power spectrum > of the voice. Thanks for your help. > > Happy holidays everyone! > > 73, > > Ron (KA3J) > > > > > Yahoo! Groups Links > > <> To visit your group on the web, go to: > http://groups.yahoo.com/group/emrfd/ > > <> Your email settings: > Individual Email
273	2006-12-26 16:37:55	ka3j12	Re: Voice Power Spectrum Density
Thanks for the help folks! The information confirms that one can sacrifice the low end of the spectrum and still maintain decent intelligibility at the cost of naturalness. 73, Ron (KA3J)