Bill Unruh wrote: > On Sun, 21 Dec 2008, Jamie Lokier wrote: > > > > >But then there's people who say that all analogue output above 20kHz > >or so is pointless anyway. :-) (I have no opinion either way on this. > >On the one hand, they could be right. The upper auditory limit is > >well known. On the other hand, there is a possibility that IMD occurs > >in the ear due to physical non-linearity, making it able to extract > >information from higher frequencies in a rich sound field, even though > >those frequencies cannot be heard by themselves). > > IF there were any energy there, you could be right. I'm not sure how I could be right since I didn't express an opinion one way or another :-) > But there isn't or should not be. recordings should roll off the > audio above 20KHz, and anyway music etc has no energy there anyway, > and the ear is very insesitive to it as well. There are no > components of the sound to introduce the IMD from whatever > non-linearity. The components are not from the music, they are from all the distortion and aliasing we've been talking about, from DAC and filter imperfections. They are components you don't want any of at all from the speakers, but cannot totally eliminate. What the ear is sensitive to is very difficult to measure in this context. We're not talking about sensitivity to individual sounds, but to whether it extracts any psychoacoustic consequence from their presence among other sounds. How do you reliably measure that? -- Jamie ------------------------------------------------------------------------------ _______________________________________________ Alsa-user mailing list Alsa-user@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-user
