On Sep 15, 2009, at 1:11 PM, Joe Hankins wrote: > I > operation was effective radiotelephone service. Human speech falls > into > the range between 300 and 3000 Hz. There are sounds outside this > range, > but they do not contribute to intelligibility.
That's actually a complete myth. There are frequency components both above and below this range which, if present, contribute in a major way to speech intelligibility. The fundamental frequency in vowels is closer to 100 Hz, and frequencies well above 3 Khz (actually above 4Khz) are needed to reliably distinguish an "f" from an "s". There are also significant intelligibility cues in the 20-80Hz range for some consonants. 300-3000 hz was convenient for the phone company and was proselytized by Collins (which we all know is never incorrect in design philosophy) as the gospel truth. But it contributed mostly to Uncle Bob and Granny being so hard to understand and sounding so lousy on the telephone. And contributes still to "pinched" sounding radios. Your modern telephone (fortunately) exceeds this old accepted range in bandwidth. Grant/NQ5T ______________________________________________________________ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/[email protected]/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: [email protected] To unsubscribe, send an email to [email protected] with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
