On Mon, 26 Nov 2007 10:52:17 -0800 (PST) Bill Unruh <[EMAIL PROTECTED]> wrote:
> On Mon, 26 Nov 2007, Sergei Steshenko wrote: > > > On Mon, 26 Nov 2007 18:19:24 +0100 > > Benoit Rouits <[EMAIL PROTECTED]> 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 every zero crossing, the sampled signal will be 0/zero/null/zilch - you name it. The point/problem that the original poster suggested input signals with fundamental being the exact Nyquist frequency. --Sergei. ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
