Re: High-frequency hearing in humans

["Hermes, D.J." <D.J.Hermes@xxxxxx>]

Just to show that it is not a simple question of loudspeaker quality but also of recording quality I send you a Matlab script producing one square wave "sampled" at 48000 and another at 192000 Hz.  The difference is audible through any loudspeaker.  

clear all
sf1 = 48000;
sf2 = 192000;
dt1 = 1/sf1;
dt2 = 1/sf2;
du = 1;
f0 = 5000;
t1 = 0:dt1:du;
t2 = 0:dt2:du;
s1 = square(2*pi*f0*t1);
s2 = square(2*pi*f0*t2);
sound(s1, sf1)
wavwrite(s1, sf1, 's48000')
pause(1)
sound(s2, sf2)
wavwrite(s2, sf2, 's192000')


Best,
Dik

> -----Original Message-----
> From: AUDITORY - Research in Auditory Perception
> [mailto:AUDITORY@xxxxxxxxxxxxxxx] On Behalf Of Joachim Thiemann
> Sent: vrijdag 4 februari 2011 15:37
> To: AUDITORY@xxxxxxxxxxxxxxx
> Subject: Re: [AUDITORY] High-frequency hearing in humans
> 
> On Thu, Feb 3, 2011 at 23:08, Kevin Austin <kevin.austin@xxxxxxxxxxxx>
> wrote:
> > A colleague of mine has been working on clicks in an electroacoustics
> aural perception course. He discovered that a 48kHz sampling rate was
> "too crude", and that working at 96kHz (or higher), the differences
> between clicks over 8kHz were noticeable. This is not quite what
> sampling theory seems to say. At 44.1kHz, a single sample click
> represents 22kHz, and a two sample click represents 11kHz. How does one
> represent a 16kHz click with a 44.1kHz sampling rate?
> 
> I think one has to be careful about the actual D/A hardware in these
> cases.  Oversampled sigma/delta? R-2R? What are the postfilter
> characteristics?  I think with these type of stimuli, differences
> might be audible: even if the same soundcard is used at different
> rates, the filter should change.  The differences in filter
> characteristics might extend to lower frequencies, where they might be
> picked up by individuals with good hearing.
> 
> Joe.
> 
> --
> Joachim Thiemann :: http://www.tsp.ece.mcgill.ca/~jthiem