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Steve Guttenberg compares subjective and objective reviews

RayDunzl

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Is the floor missing something in that photo?
 

amirm

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To paint the larger picture, what you hear from a speaker is the sum total of direct sound coming at you from the speaker, and reflections from the room surfaces. Speaker response can vary from direct to reflected so any proper model of the speaker needs to include those. Using perceptual and practical modeling of rooms, Harman has created the weighting factor for those reflections by correlating the objective measurements against subjective listening tests.
 

amirm

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Is the floor missing something in that photo?
Anechoic chambers don't have floors. It is usually a mesh. That room was small and I could not get far enough back to show the floor.
 

dragonspit4

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You can but you need an anechoic chamber with measurements every few degrees in both horizontal and vertical direction. You then apply a special weighting based on which ones come at you directly versus reflected from horizontal and vertical directions (indirect sounds). Once there, you get extremely high correlation to listening tests. It is not perfect and listening tests needs to confirm but it is a very good predictor.

Here is a picture of the setup I took while visiting Harman in one of their anechoic chambers:

View attachment 20016

That is the vertical arc with microphone array placed at the precise angles. The speaker is put on a turntable that is spun and the output of the microphones is captured. Once done, you have a sphere or response all around the speaker where you can now begin go create the composite score of all the direct and indirect sounds per above.

This is pretty interesting.
How about for headphones, can the same thing be done
Can we measure all the frequency response of different headphones (from same brand or different brand), and determine which one sounds the best? (determine best headphone by frequency response) and make an objective claim that one headphone is superior in sound compared the others?
I am assuming that measuring headphone's frequency response would be easier? since there is no reverberation (echo) of sound coming from the walls?
 

Cosmik

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...what you hear from a speaker is the sum total of direct sound coming at you from the speaker, and reflections from the room surfaces.
What reaches your ear is what you describe above. What you hear is dependent on functions of the ears and brain, and possibly what you consciously choose to focus on.
 

flipflop

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Can we measure all the frequency response of different headphones (from same brand or different brand), and determine which one sounds the best?
Yes, to a large degree. From 'A Statistical Model That Predicts Listeners’ Preference Ratings of In-Ear Headphones: Part 2 – Development and Validation of the Model' (Sean E. Olive, Todd Welti, and Omid Khonsaripour):
The correlation between the predicted and measured preference ratings was r = 0.91 with a residual error of about 5.5% or 5.5 points on a 100-point preference scale.
I am assuming that measuring headphone's frequency response would be easier?
It poses different obstacles due to leakage effects and driver position variability.
 

amirm

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vert

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Reading from the website of Paradigm, their research with the Canadian institute had similar results in that listeners expressed some definite preferences in speaker profiles.
 

amirm

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Reading from the website of Paradigm, their research with the Canadian institute had similar results in that listeners expressed some definite preferences in speaker profiles.
Paradigm is a spin off from NRC research team (of which so is Dr. Toole). PSB is another company in the same regard.
 

Biblob

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Paradigm is a spin off from NRC research team (of which so is Dr. Toole). PSB is another company in the same regard.
Little bit offtopic, but I just looked up PSB and saw that they just released a new Alpha series of budget-friendly speakers. They look nice :)
 

HuskerDu

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...All of this research is extensively documented ... It all points to ... smooth ... [speaker] frequency response.

Finally found this!

So I'll look around to see if I can find a smoothness ranking, but if anybody already has it, I would of course welcome a link.

I did find the Zu measures using the search suggested early in this thread. Ouch I think. I'ma look for my receipt next, to check whether 60 days are up already.

Glad to have the speaker performance target nailed down: flatness per dollar, assuming the (presumably axiomatic) engineering for getting the signal from the amp to the speaker (ohms I gather...) is competently addressed.
 

HuskerDu

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...see if I can find a smoothness ranking, but if anybody already has it, I would of course welcome a link.

Found Atkinson. Can't find a set of charts that are like the ones in the Zu speaker article. Smooth frequency response is much too vague for Google, as I've deployed it so far.

Found one post that points out a (now) obvious tidbit: put the speaker on the grass outside and you've got a low-tech anechoic test bench. (I'ma think about this. Flat freq resp can't be that hard to test, in pragmatic terms. Sound waves travel pretty slowly... Still feels like I'm catching up with the "obvious" though.)
 

Blumlein 88

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I think what you are looking for is a Directivity Index or DI from the spin-o-rama data.

Here is a good slideshow presentation with some explanation.
https://www.sausalitoaudio.com/wp-content/uploads/2018/07/Interpreting-Spinorama-Charts.pdf

Here is a 7 page article by Floyd Toole explaining DI and spinorama results.
https://www.edn.com/design/audio-de...ring-the-essential-properties-of-loudspeakers

It is explained here also.
https://www.audioholics.com/loudspeaker-design/understanding-loudspeaker-measurements

Sorry for the scattershot approach some explanations are easier for a given person than others.

Here is another explanation in terms of the ANSI standard.
https://speakerdata2034.blogspot.com/2019/02/spinorama-cea-2034-2015-ansi-data-format.html
 

Daverz

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Found Atkinson. Can't find a set of charts that are like the ones in the Zu speaker article. Smooth frequency response is much too vague for Google, as I've deployed it so far.

Also check out the measurements for the Devores they all love at Stereophile.

Found one post that points out a (now) obvious tidbit: put the speaker on the grass outside and you've got a low-tech anechoic test bench. (I'ma think about this. Flat freq resp can't be that hard to test, in pragmatic terms. Sound waves travel pretty slowly... Still feels like I'm catching up with the "obvious" though.)

Should the mic go on the grass, too? I live on an abandoned golf course, and have thought of schlepping speakers out there for measurement.
 

HuskerDu

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Should the mic go on the grass, too? I live on an abandoned golf course, and have thought of schlepping speakers out there for measurement.

As I understood it, the speaker goes on its back (face up) and the mic goes above (straight up) the speaker. As I'm seeing the terms used, I want to say this gives "on axis" measurement. (... I picture myself standing there holding the mic out in one hand and pushing "play" with the other hand, and no hands left for swatting mosquitos.)
 

HuskerDu

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I think what you are looking for is a Directivity Index or DI from the spin-o-rama data.

Here is a good...

First off: Thank you @Blumlein 88 for taking the time to bring those links together. Awesome!

I was never sure, when I read references to "spin-o-rama," that the term was legit. Like "shout-o-meter." Now I get it. The Audioholics version is clear enough that I'll pass on the $105 for the ANSI white paper, but it's very cool that there is an ANSI standard for this. ;-)

In the Audioholics article, Mr Larson writes, "Audioholics publishes these measurements in our reviews of bookshelf speakers, and, as far as we know, we are the ONLY third-party publication to do so."

Ugh. I was looking for a chart for. every. speaker. ...Seriously. The internet is a wonderful thing but I guess thousands of dollars are at stake here.

@amirm, do your buddies at Harmon run every competitor's speaker through that room of theirs? If so, who can I call to get a login to the data?

On a different tack, can we boil this down a bit, like crowd-sourcing?

I'll try for some examples to show my intent, but I apologize that I'm not technical enough to make real suggestions. Here goes...
  1. When the slope of the line for frequency-to-amplitude goes away from flat, we could express that as a number, right? So the first gate would be +/- 3 db, except for the tails. The second gate would be the slopes as a surrogate for "smoothness" -- if we can find a calculus professor to help with slope.
  2. I have a picture (in my head) of speakers wrapped with pillows, and bungee cords to hold em. ;-) Cheap but effective? In my imagination, I make a PVC snorkel for any ports, and run the PVC through a motorcycle muffler to kill that noise. Now I have silenced everything but the drivers themselves, so we can (finally!) measure the drivers themselves.
  3. Remove the pillows and PVC and repeat. This is the noise chart.
  4. Three numbers result: high freq, low freq, flatness or slopes? As a bonus, we have the spread between with-pillows and without-pillows as the surrogate for how much room correction you're going to need... (I'd call this "noise.") I guess a further refinement could be just high and low end points, with breaks if the slope has the effect of creating gaps in the flat.
  5. ... But who has these numbers for each speaker???
As I perceive this stuff now, it's flat or it doesn't count at all, and it comes from the driver or it's noise. (Just sayin' ;-)
 

HuskerDu

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Steve doesn't know his ass from a hole in the wall. However, he is fun to listen to.
I honestly don't think we can blame reviewers using their ears when the industry as a whole apparently disregards fact altogether. (I apologize to the exceptional cases for this sweeping generalization.)
 
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