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jteef 29th May 2002 09:34 AM

The current state of psychoacoustics
 
With all the heated debates in the world today over who can actually hear what, whether 10 dollar resistors and 50 dollar caps have a place in audio electronics or whether 6N silver foil teflon insulated wire with optional gyroflux capacitor terminations sounds any different than a rusty steel flag pole; I've been wanting to find credible papers, articles, and the like that present research related to psychoacoustics.

The first (and only) of the high profile publications I can think of is the Fletcher-Munson study, but that was published some 60 years ago. I have seen other studies, and references to them but didn’t care to write down anything for further investigation at the time. I wonder if they’re even giving ph.d’s for this kind of research now or not. I would love to read some recent papers if they are though.

In my current state as an (very inexperienced) engineer, I think you are a lot better off either knowing or having researched what is better regardless of its price or "audibility" and make your design decisions with that knowledge rather than always working on the cutting edge or worse, completely disregarding them because "it might not make much of a difference." I have a general disregard for price/performance ratios in favor of a more absolute performance approach, which is the biggest advantage to DIY in my mind since it would probably run you broke in the commerical market either as a mfgr or a consumer.

To relate a story, the recent AC regeneration thread piqued my interest so I was talking about it with a friend and thinking of a few different ways to implement the idea when somebody else chimed in claiming the idea was ridiculous and backing his statement up with such phrases as: “DC is DC”, “My amp has 200uV of ripple on the supply rails” and finally “It doesn’t matter, you can’t hear less than 1% distortion anyways.” While this debate was fairly amusing to me it was also a bit irksome for a couple of reasons. I can’t believe that a reasonably educated person could dismiss something so quickly for being essentially “too good” in his mind. Secondly, where do people come up with all of these seemingly random statistical factoids and what is the real story?

So anyways, I am in the mood to read some psychoacoustics articles and would appreciate links, or references to journals/ magazines, etc preferably not financed by those doing the selling.


jt

mrfeedback 30th May 2002 02:13 AM

Physics Acoustics
 
Hello jteef,
The psychoacoustics thing is to do with noise spectrums and intermodulation products.

Eric

Bill Fitzpatrick 28th June 2002 11:34 PM

See what happens when you start looking for facts? Your post is all but ignored except for that inane comment by mrfeedback.

One good book but a little heavy is "Spatial Hearing" by Blumenthal, I believe. I have some stuff but it's a paper here and a paper there. People don't often cite research papers around these forums. Manufacturers blurbs, magazine reviews and uninformed opionions seem to be top dog.

I have some AES (Audio Engineering Society) reprints on psychoacoustics that might be of interest. You can either copy them or I can give you the reprint number and you can order them from the AES. You may want to check their web site first. It's possible that they list everything available.

Electro 29th June 2002 12:21 AM

Wait until we know more about the brain and design brain simulations to test each audio technology.

This might sound to sci-fic but it will be coming real in the future.

Right now I'm going to stick with on what I hear or see from devices that I make.

Brett 29th June 2002 12:23 AM

Bill,

I'd be interested in the preprint numbers of articles you think are valuable please. I have a list of other ones I'd like to order from them soon. Thanks.

jt.
Many of the old papers such as Fletcher Munson are still valid, as human hearing has not changed in this time. I often find the older works to be more thorough and detailed, and only in a few instances, significantly improved upon. For example, if you were asking about acoustics, Harry Olsen's Acoustical Engineering is the basic reference work and is from 1940. Until you have a good understanding of these landmark works, it's hard to advance beyond them.

Psychoacoustics is not a field with much interest in it now, so much of the work done, is by smaller orginisations or private companies, and so might not be obtainable, and could probably just be dismissed by many. Read it all with an open mind, yet do not beleive all of it. There are people at both extremes (objectivist and subjectivist) who get caught in their dogmas at the expense of learning something new.

For engineering (I presume EE and acoustics) also read everything you can by Norman Crowhurst, D.E.L.Shorter, Harry Olsen, F. Alton Everest and Malcolm Hawkesford to name a few of the top of my head. There is often vast amounts of information contained here, that can take years to understand.

Whilst I respect Bill's viewpoint, I don't <i>entirely</i> agree with it. There is a ton of snake oil out there, and some of it's hysterical. Not all of it is fraudulent or rubbish. I can hear topological (most important) and component changes. Most component changes are not huge improvements, but in combination, a number of well chosen ones can make a significant difference. Lots of experimentation over years has improved my hearing abilities (ability to discern), and I've spent lots of time in front of a spec-an, CRO, and used other disinterested non audiophilles to help correlate and corroborate changes. At heart I'm a lazy bastard: if a few op amps and electro caps for $50 worked perfectly, I'd use them. but for me they don't, so I try other things, change back, try something else and slowly narrow in on what works, all the while trying to keep a reference so I don't go too far off track. My results may not be universally applicable, but neither are those of people who peer at a display and tell me I can't hear this or that, when I know I can.

Try the experiments for yourself. I'd be interested in your findings.

Cheers

CHRIS8 29th June 2002 01:45 AM

I really have very little to say on this subject directly.
But, I am not immediately aware of ANY credible studies that have performed to conclude audible differences of specific components such as cables, caps, etc. ALL studies that have been performed using blind/double blind type testing on specfic components(mostly cables/ic) have resulted in null results. That is, with the equivalent of 50/50 statiscal scores. Not proving their are not differences, but not proving their are either. However I should point out that the studies that have been done can not be considered credible because they were not conducted with the nescarry controlled measures, and then published and peer reviewed for validity. Why? The cost. No motivation is present that I am aware of to warrant the immense cost of scientifically verifiable tests. You may presume it is a simple task to compare two items, but it is indeed not. The minimum requirements of such extensive studies require massive resources, very high number of test subjects, verified accurate switching systems, large samples of similar products, and of same products to eliminate possible 'batch' inconsistencies, etc etc etc. While some comparisons/tests that have been performed may have accurate 'controls' seemingly, are not adequate according to scientifical research procedures.


The best that I can do is to provide the general data that has been concluded by the tests that have been performed. It is up to you to come to your own conclusions. I can not verify the accuracy of all of the data contained on the following links. Sadly, due to lack of credible testing, you must use your own judjement when reading some of this. Most of this data is 'naysayer' oriented but that seems to be a result of reality. I can ONLY conclude that controlled testing is a valid way to determine the threshold of audibility in order to differentiate like components. I have provided what links were immediately available.

You can read about specific testing methods for audio reviewed by Levanthol:

J.AudioEng.Soc.,Vol.34,No.6, 1986, June

J. Audio Eng. Soc., Vol. 35, No. 7/8, 1987 July/August

AES convention paper, comparing amps:

David Rich and Peter Aczel, 'Topological Analysis of Consumer Audio Electronics: Another Approach to Show that MOdern Audio Electronics are Acoustically Transparent,' 99 AES Convention, 1995, Print #4053

Floyde Toole on sighted tests:

Toole, F. E. and Olive, S. E. ' Hearing is Believeing vs Believing is Hearing: Blind vs Sighted Listening Tests ond Other Interesting Things,' 97th AES Convention, Nov 1994, Print #3894

A debate in Sterophile about comparator(ABX) type testing:

http://www.stereophile.com/showarchives.cgi?141

A blind comparison of a Yamaha and a Pass amplifier, VERY interesting:

http://groups.google.com/groups?q=Pa...ust.net&rnum=1

Various information concering wires/amplfiers:

http://www.sundial.net/~rogerr/

Famous(Infamous?) John Dunlavy's opinion:

http://www.verber.com/mark/cables.html

Forbes magazine article:

http://www.forbes.com/forbes/98/1228/6214066a.htm

Some info on blind testning of speakers at NRC:

http://www.mastersonaudio.com/features/20010115.htm

Some info on placebo effect(should be noted this is from a naysayer site, the ABX people):

http://users.htdconnect.com/~djcarlst/abx_plac.htm

Some interesting results on various ABX product comparisons:

http://users.htdconnect.com/~djcarlst/abx.htm

Various refernce material, which the ABX testing people base their reasoning on as published on their web site:

Acoustical Society of America, Hearing: Its Psychology and Physiologogy, American Institute of Physics

Andersen, Hans Christian, "The Emperor's New Clothes"

Andersen's Fairy Tales, with biographical sketch of Hans Christian

Andersen by Thomas W. Handford. Illustrated by True Williams and others., Chicago, Belford, Clarke (1889)

Armitage, Statistical Methods in Medicine, Wiley (1971)

Burlington, R., and May, D. Jr., Handbook of Probability and Statistics with Tables, Second Edition, McGraw Hill NY (1970)

Fisher, Ronald Aylmer, Sir, Statistical Methods and Scientific Inference, 3d ed., rev. and enl., New York Hafner Press (1973)

Frazier, Kendrik, ed., Paranormal Borderlands of Science, Prometheus Books (1981)

Grinnell, Frederick, The Scientific Attitude, Boulder, Westview Press (1987)

Hanushek, E., and Jackson, J., Statistical Methods for Social Scientists, Academic Press NY (1977)

Kockelmans, Joseph J., Phenomenology and Physical Science - An Introduction to the Philosophy of Physical Science, Duquesne Press, Pittsburg PA (1966)

Lakatos, Imre, The Methodology of Scientific Research Programmes, Vol. 1 , Cambridge University Press (1978)

McBurney, Donald H., Collings, Virginia B., Introduction to Sensation/Perception, Prentice Hall, Inc., Englewood Cliffs, NJ 07632 (1977)

Moore, Brian C. J., An Introduction to the Psychology of Hearing, 3rd Edition , Academic Press, London ; New York (1989)

Mosteller and Tukey, "Quantitative Methods", chapter in Handbook of Social Psychology, Lindzey G., and Aronson, Eds., Addison-Wesley (1964)

Neave, H. R., Statistical Tables, Allen & Unwin, London (1978)

Norman, Geoffrey, R., PDQ Statistics, B. C. Decker Toronto, C. V. Mosby St. Louis, (1986)

Rock, Irwin, An Introduction to Perception, Macmillan Publishing Company, New York NY (1975)

Scharf, Bertam, and Reynolds, George S. Experimental Sensory Psychology, Scott Forseman and Company, Glenview IL (1975)


Their are plenty more links you can find in websearches, but the ones I have collected hear are just an example of the typical stuff you will find. I certainly wish that truly credible data was avaialble, but this is it.

-Chris

Bill Fitzpatrick 29th June 2002 02:12 AM

:confused:

Can someone tell me how this works?

The last post on this thread was a month ago. Nobody was offering jteff any worthwhile info. I jumped in to offer what I can and all of a sudden this thread is a hive of activity!

Anyway it's alive again and as well it should be. A super thanks to CHRIS8 for his list of references and links.

mrfeedback 29th June 2002 02:16 AM

Bill, please define what you understand by the term 'psychoacoustics ', so that we are sure that we are discussing the same subject.

Eric.

Bill Fitzpatrick 29th June 2002 03:00 AM

How the brain interprets or mis-interprets what is actually arriving at the ears.

mrfeedback 29th June 2002 03:35 AM

Or do you mean how listeners interpret minor changes in frequency response, noise and intermodulation products ?.

Eric.


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