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In Reply to: Extended Frequency Range: Effect on Perceived Speaker Sound posted by tlyyra on April 19, 2007 at 05:22:55:
If I remember correctly that study contains, according to Kal Rubinson, who is degreed neuroscientist, methodological flaws.
I've read that paper, can't remember in detail what's in it, did they test the supersonic signal on its own and measured the response?As for the highest praise in listening tests, keep in mind that probably none of these were done under controlled conditions, so the results are questionable.
Follow Ups:
Oohashi published two papers on this issue, the first at a 1991 AES convention (no peer review), the second in J. Neurophysiology 2000 (peer-reviewed). In both papers the HF content alone is presented to the subjects and response is measured.In this respect, the AES paper describes two experiments, one with genuine Gamelan music, the 2nd with simulated Gamelan music, derived from white noise.
In the 1st case, 6 out of 16 subjects responded to the HF signal, in the 2nd case only 2 out of 16. The paper does'nt provide any statistical analysis whatsoever.
The 2000 paper presents the HF results in statistical terms only.
Anyway, I think that such studies are, as interesting as they may be in themselves, of little value to the music lover since hi-rez audio formats appear to have no commercial success.
Klaus,You are right about the last point...
But the 2000 paper (or am I totally misremembering it from yesterday?) beamed to the subjects the same material thrice: (1) audible range only (below 20 kHz); (2) HF content only (above 20 kHz); and (3) "full range" (both). The response appeared only in case (3), but only in the form of a subliminal physiological reaction and subjective listening preference as gathered from the questionnaire responses. In no case did the subjects report "hearing" any HF content.
I am not convinced that the HF content produced no IM distortion effects in the audible range, and hence, it does not seem to me that ultrasonic hearing is established by Oohashi et al. Kaoru and Shogu used more than two drivers, I think. Also, Kaoru and Shogu showed measurements to determine whether there was any IM distortion produced in the audible range.
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"Opposition brings concord. Out of discord comes the fairest harmony."
------Heraclitus of Ephesis (fl. 504-500 BC), trans. Wheelwright.
Just curious, do you know how "detecting" the LF/HF contents in the audio clips was confirmed in their study? Was this detection about "hearing" the signal (the usual way, through ears) or did they use some other form of physiological monitoring?I couldn't find this paper online except as a $20 download, so I
only read the abstract.In either case, the possible presence of IM distortion might mean many things or nothing really, but it's hard to say without knowing the test setup and procedure.
I'll send you a copy tomorrow.
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