Originally Posted by Seidhepriest
That humans cannot hear well above 22050 does not mean gear can't.
Well, the point is surely what we as humans can hear, we know that our ears are very poor compared to some animals and a lot of measuring kit, but if we cant hear it is pointless to worry about capturing it.
|That humans cannot discern well above 20 KHz also doesn't mean they can't actually "hear" and be affected by such frequencies.
Actually if you cannot detect the presence or absence of a signal above 20K and sufficiently above the ambient noise level it is reasonable to say you cannot hear above 20K (at that volume level and under those conditions), you might
experience it in some other way but that is not hearing which is the point at issue.
An interesting paper, well explained, I just have a few issues with it.
1) The listening tests were not blind in the sense that they took a known ABBA form , i.e the listeners knew that A and B were not the same , thus of course they could tell a difference since they knew they were different a priori. This is a fatal flaw.
2) The graphs are pretty poor but if you zoom in on them you find that the HCS and FRS sound spectrograms are not quite the same below 20K, thus the test is invalid to start with.
3) Oohashi is indeed a PhD, he is a Doctor of Agriculture, he is less qualified to do this neuro-physiological analysis than I am , I have two degrees in Psychology and I would not call myself adequately qualified to do that part. Yet he gets first authorship on the paper, this is strange and a little bit iffy.
4) Oohashi has a patent out on a therapeutic device based on high frequency sound generation, thus he has an interest in the outcome of the study, this is a conflict of interest and my IRB would chuck a proposal for that study straight into the bin.
5) Oohashi designed the super-tweeter, a commercially available product and this gives him another interest in the outcome of the study, see conflict of interest.
6) Clearly the high frequency sound + normal sound, if we can trust the results has a physiological affect, but it isnt in the auditory cortex, it is in the occipital lobe and that houses most of the visual cortex, processing visual signals. Also the effect is to increase alpha wave activity. Increasing alpha wave activity actually results in relaxation. Thus the sound plus hypersonic sound is causing a relaxation response. So the subjects relax more, this means that they are inevitably going to ascribe positive attributes to this stimulus, note also which ones 5/10 are affected, these are entirely predictable. Thus what we have here is pretty much a smoke and mirrors job and nothing to do with hearing.
7) Meyer and Moran (2007) - stripping the High frequency sound from High res recordings by downsampling - 500+ trials, not one subject detected the difference. There are similar AES papers from 1980 that show the exact same effect for filters at 20, 18 and 16K. Let me hunt them down and I will provide exact citations.
8) See also - NHK Laboratories Note No. 486 - Perceptual Discrimination between Musical Sounds with and without Very High Frequency Components
Toshiyuki Nishiguchi, Kimio Hamasaki, Masakazu Iwaki, and Akio Ando
PREPRINTS- AUDIO ENGINEERING SOCIETY
Similar to the Meyer and Moran paper. One out of 36 subjects could detect a difference but when retested could not repeat this feat.
9) Audio Engineering Society Convention Paper 5401, presented at the 110th Convention, 2001 May 12-15, Amsterdam, The Netherlands:
"Detection threshold for tones above 22 kHz," by Ashihara Kaoru and Kiryu Shogo, National Institute of Advanced Industrial Science and Technology 1-1-4 Umezono Tsukuba, Ibaraki 305-8568, Japan.
Suggested that the effect that Oohashi et al got was due to intermodulation distortion. Ultrasonic components can intermodulate with signals in the audible range and produce intermodulation products in the audible range. When the ultrasonic components were sent to separate drivers, intermodulation was avoided, and the DBTs no longer showed that the listeners could detect the presence of ultrasonic components.
A serious citation please.
|It won't be "perfectly adequate". Real dynamic range of 44.1/16 is ~80 dB. Anything outside of that is already severely limited. Try creating a 16-bit 44100 Hz wave file in any editor (Cooledit/Adobe Audition, Soundforge, etc.) and see how low the editor will even allow a test A440 sine to go. It won't be capable of generating anything meaningful below -80 dB. It will generate at -96 just fine in 32-bit though.
I just did this in Audacity a 440Hz sine wave created at 16/44.1, I have selected some excerpts from the analysis - so not to waste bandwidth
Frequency (Hz)Level (dB)
|This is why, by the way, the better-sounding CD players have oversampling and 20-bit+ DACs.
This is an opinion.
|Many CD players have an SNR of 84-88 dB. Apple IPods have an SNR of 90 dB. Cowon players have an SNR of 95 dB, and it shows instantly. The clarity of an expanded dynamic range is quite obvious. This means, by the way, that the internal DA resolution of such a player is better than 16-bit (a 16-bit device cannot produce a listenable 96-dB dynamic range).
Which CD players have a SNR of 84 - 88db ?, please point me to concrete examples. And first gen players dont count. Even my $60 DVD player does much better than that, so does my $210 5 disc player and a 1990 Onkyo CD player. The last player I had that might even have gotten close to being that limited was my 1984 Marantz CD63 which was a 14 bit player !
|The effect an amplifier has for headphones, supplying enough power to properly drive them, bringing out detail and presence, is similar to the effect 32-bit audio has compared against 16-bit.
Er, this is unrelated to what you said last time which was that a headphone amplifier increases dynamic range which I believe I showed to be misleading.