On Mon, 26 Nov 2007 10:52:17 -0800 (PST)Bill Unruh <unruh@xxxxxxxxxxxxxx> wrote: > On Mon, 26 Nov 2007, Sergei Steshenko wrote:> > > On Mon, 26 Nov 2007 18:19:24 +0100> > Benoit Rouits <brouits@xxxxxxx> wrote:> >> >> Le dimanche 25 novembre 2007 à 18:26 +0300, Vladimir Mosgalin a écrit :> >>> That's the main reason why I asked - I heard that people can hear> >>> 22khz or about that when they are young, than listening gets worse and> >>> they don't hear very high frequencies anymore - and since I consider> >>> myself still young ;), I was kind of disappointed by the fact that I> >>> can't hear not only 22khz, but even 20khz, and when I discovered that> >>> I can't hear even 18khz, I was kind if scared - is my hearing going> >>> down due to headphone usage? Thanks for clarifying this issue.> >>> >> Theorically, A 44100 sampled audio CD can reproduce a triangle signal> >> at 22050 Hz.> >> > No, it can't.> > Sure it can. The difference between a triangle wave and a square wave a> 22000 is harmonics whose frequency is far higher than 22050. Ie, the> harmonics are irrelevant. Thus a triangle, a square, a sine, a sawtooth are> all the same. One could say that the triangle is closer since it has lower> amplitude harmonics than most of the others.> > > >> > Draw timing diagrams with different relative phases of the signal and> > sampling frequencies.> >> > Your output will be 22050 Hz 50% duty cycle square wave whose amplitude> > (and polarity/phase) depend on the above relative phase. I'm saying it again - just draw the suggested timing diagram. It will be a very good illustration of aliasing. Furthermore, if the phase is such that sampling occurs at everyzero crossing, the sampled signal will be 0/zero/null/zilch - you nameit. The point/problem that the original poster suggested input signals withfundamental being the exact Nyquist frequency. --Sergei. -------------------------------------------------------------------------This SF.net email is sponsored by: MicrosoftDefy all challenges. Microsoft(R) Visual Studio 2005.http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/_______________________________________________Alsa-user mailing listAlsa-user@xxxxxxxxxxxxxxxxxxxxxxxxxx://lists.sourceforge.net/lists/listinfo/alsa-user
