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WillWeber
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Acoustic measurement technology progresses

Can we measure what we actually hear? This has been a hot button issue throughout high-end audio pursuits, er "debates."

Optic science is helping get us closer to that goal, by allowing measurement of the acoustic waves in air. Check out this link:
photonics.com/Article.aspx?AID=48967&refer=weeklyNewsletter&utm_source=weeklyNewsletter_2011_11_10&utm_medium=email&utm_campaign=weeklyNewsletter

Actually the laser vibrometer is measuring the vibration of a membrane panel in the acoustic field. The vibration modes of the panel can be easily predicted and/or calibrated to deconvolve any influence of its modal nature.

This is a powerful tool. The current focus (so to speak) is to assist in better speaker design. In the future, this technology should allow us to unravel all kinds of mysteries. For example, does a cable "upgrade" really change the sound, and how, and how much? Does this or that tweak really do anything? How can we optimize room treatment?

I bet John Atkinson would love this instrument!

An even more direct and expedient approach is to measure the change in optical refractive index of the air directly, in 3D. This is the domain of acoustic holography. The sensitivity of this technique is not adequate, at least not yet.

John Atkinson
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Measuring What We Hear

WillWeber wrote:
Can we measure what we actually hear? This has been a hot button issue throughout high-end audio pursuits, er "debates." Optic science is helping get us closer to that goal, by allowing measurement of the acoustic waves in air. Check out this link: photonics.com/Article.aspx?AID=48967&refer=weeklyNewsletter&utm_source=weeklyNewsletter_2011_11_10&utm_medium=email&utm_campaign=weeklyNewsletter .

 

I saw a demonstration of something similar when I visited B&W's research lab in 2004. You could see the propagation of the soundwave from a speaker.

However, while this is a very useful tool, it still doesn't address the problem with quantifying perception of audio. As I explained in my AES lecture last month and reiterated in a subsequent podcast - see www.hometheater.com/content/podcast-84-john-atkinson, tools like this as well as the traditional measurements examine the quality of the signals whereas what matters to the listener is the quality of the mental constructs he creates as a result of those signals reaching the ears. These are 2 different realms.

John Atkinson
Editor, Stereophile

WillWeber
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brain waves

Thanks for your response John,

Yes, of course, our biology and psychology are unique to each of us. So "perception" is a different realm, and a challenge to measure. We can't control that part of the chain with purchases of equipment, unless drugs are considered "equipment." My opening line "Can we measure what we actually hear?" is a cheeky attention getter, as you did in the title of "...negative waves...".

If audio reproduction is to be precise as possible, the goal being to closely re-enact the live experience, measuring acoustic waves will allow us to make design and purchase decisions to that end. It would be my same biology and psychology (well sometimes) that experiences both live vs. reproduced sound.

I was involved in laser heterodyne velocitometry and holography for ultraprecision metrology in the late 70's, which are the early roots of this kind of tech. I am glad to see it evolved and is reaching national standardizing and testing labs like NPL. This or similar tools will lead to better designs, product testing, and tweak proving or debunking. Impatiently, I hopeso, soon! Or I might have to do it myself.  ;-}

Cheers,

WillW

D3sign3r
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variability

I'd like to explore the uniqueness further 

Sound is to do with the movement of air -we all live at different altitudes - barametric pressure change - thermal change - etc 

also what about the human condition?

Colds, virus's and other ailments that can change hearing and the responsivity of the human hearing system

I bet when JA lands with a cold and with the post illness grubbyness, even a set of Magneplanar 3.6's will sound like they're coated in syrup.

Actually that's a good point....@JA ....what do you do when testing a system if you're bunged up?

...or in USA do you just take the person who gave you the cold through litigation claiming "business disruption"?

.....I would 

mav52
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If you can't hear some of the

If you can't hear some of the frequencies as you get older ( 60 here and I know) we end up with "what we hear is what we are going to get" regardless of how great the measurements are.  We become addicted to measurements and pretty cabinets which in the end directly impacts our wallets but at what cost do you draw the line and say "it sounds and looks good to me".  In the end the persons ears will decide unless the person just happens to have a load of cash. In that case, buy it.

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