Measurements v Listening Tests

tuga

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I think there has to be a distinction between individual equipment measurements (test bench, anechoic, etc.) and that of a acoustic in room measurements of a whole system at listening position.

Where the former are next to useless above a certain acceptable level of performance to predict sound quality. The latter can describe a fair bit about the sound. However what we listen to is music, not sound, hence listening tests are vital. 
The off-axis dispersion characteristics of a loudspeaker will let you antecipate how it will perform in a room above ~300Hz because it is related to early reflections.

Floyd Toole has done extensive research in these matters:

Toole has concluded that normal reflections in a typical small living room seem not to interfere with perception of the recorded space. He has also determined that early lateral reflections (<50ms) have a beneficial effect on intelligibility similar to raising the dialog level, and that the reflection pattern is more important than reverberation.
This has led to Toole’s recommendation that too many or too few reflections can be a problem. In particular, acoustic absorption, diffusion, and reflection must be broadband, ideally starting below 200Hz. He pointed out that the typical 1˝ or 2˝ sound panel most often affixed to walls works only at relatively high frequencies, and acts to effectively turn down the tweeter with no effect on the midrange or upper bass, thus unbalancing the sound.
Toole reminded us that many of the practices to deaden a room’s acoustics came from standards for broadcast and recording control rooms, where sound details must be heard more clearly, not for general listening rooms.
Harman testing has shown that sonic anomalies which are audible while the listener is moving around become much less obvious once the listening position is essentially fixed (the listener sat down!). Toole spoke of comb filtering, and has deduced that it is an artifact of measurement, not an audible problem in normal listening. We are less sensitive to room resonances in music than in broadband noise—our hearing is sensitive to the frequency response effects, not the time domain ringing, particularly in a reflective space, due to our “multiple looks” at the signal (except in the bass range, where both are factors). Audibility thresholds decrease with repetition and duration in reflective rooms.
Humans seem to be able to adapt to a room’s acoustics, up to a point. Thus, we should be able to predict real-room performance from a proper set of anechoic measurements, except for bass issues below about 300Hz. In Harman’s listening tests, low-frequency performance accounts for about 30% of a speaker’s rating.
Harman testing has shown that speakers with a fairly flat on-axis response and with a smooth and gentle off-axis level fade and roll-off are preferred by expert and amateur listeners. A speaker with an off-axis response that differs substantially from its on-axis response cannot be corrected with an equalizer. In-room measurements lower the accuracy of the data since they include a mix of direct and reflected sound.
Since with most speakers the reflected sound has a different frequency response than the direct sound, an equalizer will cause more problems than it will cure.
(…)
Regarding bass, the Schroeder frequency is that threshold above which room resonances are considered so close together that they can be ignored with respect to frequency response anomalies. Toole has found that this works for large rooms, but the formula for its calculation yields too low a frequency for small rooms. In fact, Toole believes that calculation of room resonances is irrelevant in real home listening rooms, because not all modes have an equal effect or are heard equally, since there are multiple sources (speakers), and because all the formulas are based on a source in a corner with the measurement taken in the opposite corner (where there is never a listener). This has led to Harman’s recommendation to use four subwoofers in the center of each wall to provide the most uniform bass over the largest listening area in the widest range of small-room sizes; it reduces, and sometimes eliminates, the need for bass EQ.


‘Conventioneering’ by David J. Weinberg in Multimedia Manufacturer Magazine, March/April 2006

The latter can describe a fair bit about the sound. However what we listen to is music, not sound, hence listening tests are vital. 
I disagree with your last sentence; music is sound(s).

The Encyclopedia Britannica describes music as the "art concerned with combining vocal or instrumental sounds for beauty of form or emotional expression, usually according to cultural standards of rhythm, melody, and, in most Western music, harmony. Both the simple folk song and the complex electronic composition belong to the same activity, music. Both are humanly engineered; both are conceptual and auditory, and these factors have been present in music of all styles and in all periods of history, throughout the world."

 

insider9

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I disagree with your last sentence; music is sound(s).
Try to give an instrument to someone who doesn't know how to play it and ask them to play music. Best they can hope for is to get some sounds out. It's unlikely to resemble music. 

Music is only made up of sounds but isn't sound as such (feel free to disagree). To have music you need rhythm. That's the main reason most measurements aren't good enough to describe it. They don't have an issues with sound, easy to describe it with things like frequency, decay, etc. But how do you acoustically measure rhythm? Maybe once this is achieved we will be able to predict what system sounds like from graphs. 

 

tuga

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Try to give an instrument to someone who doesn't know how to play it and ask them to play music. Best they can hope for is to get some sounds out. It's unlikely to resemble music. 

Music is only made up of sounds but isn't sound as such (feel free to disagree). To have music you need rhythm. That's the main reason most measurements aren't good enough to describe it. They don't have an issues with sound, easy to describe it with things like frequency, decay, etc. But how do you acoustically measure rhythm? Maybe once this is achieved we will be able to predict what system sounds like from graphs. 
Audio equipment only deals with sounds; humans interpret certain sound combinations as music.

 
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MF 1000

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Audio equipment only deals with sounds; humans interpret certain sound combinations as music.
hmmm.....There must be a group of humans then that lost the ability to interpret sounds as music - aka Rappers 

 
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TheFlash

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One of the problems of this and other forums is that we all too easily slip into that either/or mentality which this thread, on the whole, appears to have avoided so far. As some here have said in different ways, it should not be a case of measurements vs listening tests as per the title but Measurements AND Listening Tests.

 
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Kevin Wood

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Comparing measurement with listening is like comparing Apples with Oranges. We make measurements to determine if the equipment is doing its job accurately and to determine what effects the room is having on the performance of the equipment. If we want to know how a system sounds, surely we listen to it instead?

We might infer certain things about the sound from the measurements - we might predict it sounding rather boomy if there's a large peak in the bassresponse caused by a room mode. Equally, we might expect it to sound rather bright if there's a peak in the upper midrange. Measurements simply aren't there to provide a description of how a system sounds although they can often provide clues to why a system doesn't satisfy, and therefore to help us find solutions.

 

General Factotum

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The car analogy is a bit complicated and perhaps not very adequate because car performance has both static and active elements, whilst a domestic reproduction system of music recordings only has a static side to it. But using the F1 analogy where lap time is the ultimate goal, this can easily be solved by removing the driver from the equation (as far as I know F1 cars have been able to go round the track by itself for a few years now).

With hi-fi equipment a single measurement will provide information about a specific parameter; for a more global perspective you need a comprehensive set of measurements, like those performed by Stereophile, Soundstage, etc. Such a set of measurements will provide a more or less detailed picture of an equipment's performance (depending on the type of equipment). In other words it will give a reasonably clear idea of the level of accuracy with which it reproduces the signal. With speakers you can even roughly estimate how a given model will perform in a room.

What measurements do not tell you, and here we agree, is whether or not you will enjoy the way it reproduces music, what it sounds like (the most accurate system would have no own sound/sonic signature). This is something that you and you alone can assess through listening, through a process that is akin to the act of tasting. It is also possible to assess accuracy through listening but that task is much more difficult to accomplish.
     As ever with such posts this one has wandered off on to something else. It's a stick with two wrong ends.

     You are of course right in your statement re F1 cars. Even cars ordinaire can quite happily drive themselves if so equipped. In the OP however I was referring to buying a Joe Soap car as a Joe Soap consumer, nothing more. "Does Sir want a Fiesta? Corsa? Punto? Car X, Y, Z?", "Umm.. dunno, pass me some keys!" Perhaps some people CAN decide such a thing on manufacturers info and dealers blurb, but not me.

     Indeed data can be produced on all audio equipment but not on how it is heard by any individual. My point was regarding the data to brain result, not the data to ear result. I don't know of any way to measure that "full audio chain" in a way that can be used to decide what specific item to buy, it would just be a horrendously complicated amalgamation of different sets of figures. When my HF drops off a bit more, I'll probably prefer a brighter sound. Again, that is just my limited experience. It could well be that some people can look at sets of equipment data/ room data/ hearing data (I'm not aware that we can even measure what the brain receives) and know how they all act as a whole, just not by me. They act as part of a decision making chain for me, not the final arbiter.  :sofa:

 
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