Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!cs.utexas.edu!usc!brutus.cs.uiuc.edu!ux1.cso.uiuc.edu!aries!forbes From: forbes@aries.scs.uiuc.edu (Jeff Forbes) Newsgroups: sci.electronics Subject: Re: I don't need HDTV! Message-ID: <1990Mar20.225851.22762@ux1.cso.uiuc.edu> Date: 20 Mar 90 22:58:51 GMT References: <9662@pixar.UUCP> <1990Mar20.162041.4639@ux1.cso.uiuc.edu> <2070@sauron.Columbia.NCR.COM> Sender: usenet@ux1.cso.uiuc.edu (News) Reply-To: forbes@aries.scs.uiuc.edu (Jeff Forbes) Organization: School of Chemical Sciences, Univ. of Illinois at Urbana-Champaign Lines: 34 In article <2070@sauron.Columbia.NCR.COM> wte@sauron.UUCP (Bill Eason) writes: >In article <1990Mar20.162041.4639@ux1.cso.uiuc.edu> forbes@aries.scs.uiuc.edu (Jeff Forbes) writes: >> >>Aren't all of the digitally mastered recordings sampled at ca. 45kHz? >>Which would make the arguemnt about CD response moot. >> >> Jeff > >Enter here the Nyquist criterion which says that the sampling frequency >(44.1 kHz really) must be >= two times the highest analog frequency being >recorded. Therefore, the highest frequency which can be accurately >reproduced from a 44.1 kHz digital recording is 22.05 kHz, which is within >the range of hearing of several folks posting here. I suspect my audible >range reaches up there, too, since I can hear department store burglar >alarms and CRT flyback transformers. > >-- >Bill Eason (803) 791-6348 ...bill.eason@ncrcae.Columbia.NCR.COM >NCR Corporation >E&M Columbia 3325 Platt Springs Road West Columbia, SC 29169 I am thoroughly familiar with the Nyquist theorem. The point I was trying to make was that a large fraction of the music today is digitally mastered at 44.1kHz which would limit all media to 22.05 kHz maximum frequency. A record made from a digital master can have no better frequency response than that of the master. Any higher frequency heard are noise. I can hear TV flyback transformers as well, but that is only 15.75 kHz. I certainly can't here it in my multisync when it is at 35kHz. I have been experimenting with piezoelectric transducers, and I can hear 17.5kHz in a noisy lab. With a quiet enviroment and more sound power I could probably hear above 18kHz. I do wonder what the actual percentage of the ADULT population can hear sine waves above 20kHz. Jeff