Just my 2 cents...
Phase and frequency response are related. If the system reaches >20kHz, it follows that the phase shift is moved up in frequency, for a more accurate time-domain reproduction of the sound. Given that the binaural system relies on this information to accurately localize sounds, it makes sense to try to get it right.
As to the physiological limits to hearing, impulses are delivered to the brain with external stimuli at 250kHz, according to research done in the USSR quite some time ago, and has been verified again semi-recently. Hence, it makes sense to try to reach this frequency.
The lower frequency limit, to my mind, should be set at the point where room response rolls off due to the finite acoustic impedance of walls, windows and so forth. This is somewhere in the range 3-5Hz. Of course, if you've got power to burn, you can measure where this pole occurs, compensate for it, and introduce another pole at 0.1Hz or so, and improve phase response.
Reason? Our perception of low frequencies is also phase-sensitive. Further, the emotional impact is enhanced, as we perceive these ultra-low frequencies with the whole body, not just the ears.
As for sine waves.. I recall that we did a test on this back in my days at school. Myself and two others (of a class of 30 teenagers) stopped actually 'hearing' the sound at 22kHz. I've got a low grade asthma, and I've been told that may be the reason. Also, girls/women have better hearing than boys/men.
It could be pointed out that, at higher frequencies, a sufficient level will give a tangible sensation of the room being larger. Not talking about music here, simply the ability to judge distances being affected. At lower frequencies, there is an equally tangible sensation of tension in the air; if you live near industrial facilities that get turned off at a certain time, you can notice the transition.
Phase and frequency response are related. If the system reaches >20kHz, it follows that the phase shift is moved up in frequency, for a more accurate time-domain reproduction of the sound. Given that the binaural system relies on this information to accurately localize sounds, it makes sense to try to get it right.
As to the physiological limits to hearing, impulses are delivered to the brain with external stimuli at 250kHz, according to research done in the USSR quite some time ago, and has been verified again semi-recently. Hence, it makes sense to try to reach this frequency.
The lower frequency limit, to my mind, should be set at the point where room response rolls off due to the finite acoustic impedance of walls, windows and so forth. This is somewhere in the range 3-5Hz. Of course, if you've got power to burn, you can measure where this pole occurs, compensate for it, and introduce another pole at 0.1Hz or so, and improve phase response.
Reason? Our perception of low frequencies is also phase-sensitive. Further, the emotional impact is enhanced, as we perceive these ultra-low frequencies with the whole body, not just the ears.
As for sine waves.. I recall that we did a test on this back in my days at school. Myself and two others (of a class of 30 teenagers) stopped actually 'hearing' the sound at 22kHz. I've got a low grade asthma, and I've been told that may be the reason. Also, girls/women have better hearing than boys/men.
It could be pointed out that, at higher frequencies, a sufficient level will give a tangible sensation of the room being larger. Not talking about music here, simply the ability to judge distances being affected. At lower frequencies, there is an equally tangible sensation of tension in the air; if you live near industrial facilities that get turned off at a certain time, you can notice the transition.
Is there any info available on the net on that subject ?
BTW: the Nyqvist theorem would apply here as well. If our nerve system "samples" 250k-times/second, an upper cutoff frequency of 125 kHz would be appropriate (maybe the DVD-Audio guys should rethink their standards ?).
Maybe I should check my bank-account and buy that TAD tweeter ?
I would at least prefer it over the diamond dome tweeter due to better frequency response and significantly lower price.Regards
Charles
phase_accurate said:
Yes, there is information available on the net on that subject. I do not, however, recall the exact titles of the papers involved. You might get lucky with Google.
As to the Nyquist theorem, it does not really apply here. Our ear uses some 30.000 absolute-phase sensitive resonant detectors with varying center frequencies and Q factor. Per ear. Impulses passed on to the brain only occur when the detectors are stimulated- in essence, a mesh of frequency-amplitude levels are passed on to the brain in real time, not samples. The brain is not, it seems, capable of processing information fast enough to actually work directly with pressure samples =)
Bearing in mind that we have two ears, it is also conceivable that even higher frequency sounds might be detected somehow.
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