Why evaluating the sound of a single speaker is essential

[krabapple]

Was that you or AI?

 

[Neuro]

The original reason for testing in mono, the one that started this entire discussion, has to do with identifying resonances in loudspeakers. These are technical faults that should not exist if we have any interest in hearing the correct timbres of recorded voices and instruments. It turns out that in the experimental method that is most revealing - double-blind equal-loudness comparisons of 3 or 4 loudspeakers - listeners could recognize resonances more readily than when listening in stereo or multichannel. It was simply a subjective way to identify audible resonances so that loudspeaker design engineers could attempt to eliminate them. These tests were time consuming and very expensive to conduct and it was fortunate that the NRCC and Harman could afford the expense of doing them. As a result of decades of these tests, we have been able to develop a measurement method - the spinorama - that visually reveals the resonances, and that has the further advantage of showing impressively high correlations with subjective evaluations of overall sound quality. As a result, the tests no longer need to be done, and they have ceased.

Stereo imaging is an entirely separate consideration. While evaluating hundreds of loudspeakers in the tests just described listeners often commented that the highest rated ones - those with the fewest audible resonances - had a tendency to "disappear", allowing a sense of distance and space that was associated with the recording. Poor loudspeakers drew attention to themselves. You may be experiencing something like this.

But, as described in some detail in the 4th edition of my book, stereo itself is a problem. It is not an encode/decode process. It is merely a two-channel delivery system, and what is delivered is what someone in a recording studio created. There are no standards. Stereo recordings that employ hard-panned left and right images/instruments are delivering essentially mono signals that will be strongly localized to the loudspeaker - it is the source. These are combined with phantom (double mono) images that have very different timbres and spatial characteristics. Other recordings avoid extreme hard pans, and these present a spatially "softer" imaging. When images appear outside the left-right span of the loudspeakers it is very likely accidental, the result of binaural processing In the mix, or you have multidirectional loudspeakers energizing strong side-wall reflections. Some classical recordings present a wide soundstage because of the high proportion of reflected (decorrelated) sounds in the mix; others have been known to deliver spatially compressed, in my view, simply bad recordings. There are no standards.

So, the listener normally has no way to separate the variables. This is a reason to start with timbrally neutral, technically accurate, loudspeakers as they will provide the most advantageous platform from which to hear what was recorded whether listening in stereo or multichannel. Of course, you may not always like what was recorded - it is art.

When comparing objective spinorama measurements with the subjective assessments of each individual speaker in the original study, I am missing some important variables. Room size and attenuation. The room affects how the direct sound is colored by the room's reflections.
How big was the room, the listening position and the speaker position? Dominant reflections, attenuation and delay? Important variables if the study is to be reproduced.
My guess from pictures of the room is that the lateral reflections dominate and the delay is about 18 ms. Attenuation about 8 dB and the frequency curves does not deviate significantly from the direct sound.

 

[LevityProject]

When comparing objective spinorama measurements with the subjective assessments of each individual speaker in the original study, I am missing some important variables. Room size and attenuation. The room affects how the direct sound is colored by the room's reflections.
How big was the room, the listening position and the speaker position. Dominant reflections, attenuation and delay. Important variables if the study is to be reproduced.
My guess from pictures of the room is that the lateral reflections dominate and the delay is about 18 ms. Attenuation about 8 dB and the frequency curve does not deviate significantly from the direct sound.

I hear you ... But The entire catalog of scientific measurements that comprise ASR reviews happens (by chance? I think not!) to correspond to what Dr. Toole is saying about the reality of flat frequency response in loudspeakers.

 

[LevityProject]

Was that you or AI

It was the singularity ...

_____
| [o o] |
| ^ |
| ___ |
___|_|___|_|___
| | |
| ----+---- |
| | |
\ | /
\_____|_____/
| |
___| |___
|___| |___|
/ \
/_________\​

 

[Floyd Toole]

When comparing objective spinorama measurements with the subjective assessments of each individual speaker in the original study, I am missing some important variables. Room size and attenuation. The room affects how the direct sound is colored by the room's reflections.
How big was the room, the listening position and the speaker position? Dominant reflections, attenuation and delay? Important variables if the study is to be reproduced.
My guess from pictures of the room is that the lateral reflections dominate and the delay is about 18 ms. Attenuation about 8 dB and the frequency curves does not deviate significantly from the direct sound.

I can only conclude that you have not read the original papers or my books, because more explanation exists, but most importantly the tests have been done over a period of about 40 years in two countries, in several different rooms (documented) with no difference in results with hundreds of listeners and loudspeakers. What you seem not to be aware of is that the tests are not of "absolute" sound quality, which includes the recording as a variable, but of "relative" sound quality in which the recordings are test signals to energize resonances, and the most revealing signal is pink noise. The purpose of the tests was to reveal problems in loudspeakers, not to see whether the loudspeakers sounded "good" with specific - non-standardized - recordings.
BTW, the direct sound, by definition, is not coloured by reflections, which apparently is one reason why it is the dominant factor in the perception of sound quality. It initiates the precedence effect and is the reference against which reflected sounds are compared.

 

[Prowler_88]

I find it hilarious that we can spend so much effort discussing the neutrality of speakers, tested listener preference etc., yet my Dad turns the bass up so high on his Sonos system (with two subs very poorly placed) whenever someone speaks the sofa shakes. Any time I have a new bit of kit to show him, he always complains there’s not enough bass. Chuck a 10db boost on everything sub 150Hz and he’s all smiles.

Joe public leave their TVs on dynamic, crank bass up to 11 and listen to music via YouTube. Meanwhile…

 

[krabapple]

Are you laughing at your Dad, or ASR?

 

[kyuu]

I find it hilarious that we can spend so much effort discussing the neutrality of speakers, tested listener preference etc., yet my Dad turns the bass up so high on his Sonos system (with two subs very poorly placed) whenever someone speaks the sofa shakes. Any time I have a new bit of kit to show him, he always complains there’s not enough bass. Chuck a 10db boost on everything sub 150Hz and he’s all smiles.

Joe public leave their TVs on dynamic, crank bass up to 11 and listen to music via YouTube. Meanwhile…

I'm not sure what your point here is. The preference for a bass bump is well documented in the research. Of course you don't need your speakers to do this, as a bass bump is easily (and better) achieved with any number of DSP systems.

Of course, the sort of bass your father's system has appears to be deeply unpleasant. I would have to wonder if he has some sort of hearing impairment.

 

[Prowler_88]

Are you laughing at your Dad, or ASR?

Both!

 

[krabapple]

Loss of bass hearing would be unusual, I think...?

 

[Neuro]

I can only conclude that you have not read the original papers or my books, because more explanation exists, but most importantly the tests have been done over a period of about 40 years in two countries, in several different rooms (documented) with no difference in results with hundreds of listeners and loudspeakers. What you seem not to be aware of is that the tests are not of "absolute" sound quality, which includes the recording as a variable, but of "relative" sound quality in which the recordings are test signals to energize resonances, and the most revealing signal is pink noise. The purpose of the tests was to reveal problems in loudspeakers, not to see whether the loudspeakers sounded "good" with specific - non-standardized - recordings.
BTW, the direct sound, by definition, is not coloured by reflections, which apparently is one reason why it is the dominant factor in the perception of sound quality. It initiates the precedence effect and is the reference against which reflected sounds are compared.

The room affects how the direct sound is perceived coloured by the room's reflections.

Subjective sound bokeh - interesting analogy.

Image bokeh is related to how the blur in the background of an image contributes to the overall perception of the image. I get bad image bokeh from old 500/8 mirror telephoto lenses with round rings in blurry parts. Good bokeh is provided by my Canon 55/1.2 and 85/1.8. The image is sharp in a...

www.audiosciencereview.com

Toole/Olives spinorama provides partially relevant but not sufficient information for perception of optimal sound bokeh.
The subjective perception in the listening position of a speaker's direct sound, dispersion patterns, the reflections in the room require more focus on more relevant measurable data.
As a senior neuroscientist with focus on brain tumors, brain anatomy and functional brain imaging, I find it strange that so little is done by colleagues with respect to how physics affects neurophysiology and neuropsychology. After reading Toole's last three editions of Sound Reproduction and downloading thousands of relevant studies I have concluded that there are many relevant areas which are suboptimally investigated and not described.
At present I have the basis for a number of review articles and very interesting studies. I lack a sounding board with some physical experience and preferably some knowledge in neurophysiology/neuropsychology. My research is published through The Karoliska Institut Sweden. Any suggestions?

Neuro

Subjective sound bokeh - interesting analogy.

Image bokeh is related to how the blur in the background of an image contributes to the overall perception of the image. I get bad image bokeh from old 500/8 mirror telephoto lenses with round rings in blurry parts. Good bokeh is provided by my Canon 55/1.2 and 85/1.8. The image is sharp in a...

www.audiosciencereview.com

 

[Floyd Toole]

Loss of bass hearing would be unusual, I think...?

Unusual I agree, but I know two people who have had bass loss suddenly occur, one recovered over time, the other not. One ear, not both.I don't know the mechanism but it is not the "normal" kind of hearing loss.

 

[kyuu]

Loss of bass hearing would be unusual, I think...?

Yes I think so, but the described listening patterns suggest regular exposure to wildly excessive SPL in the bass region.

 

[bmc0]

Loss of bass hearing would be unusual, I think...?

It's fairly rare, but does happen. Ménière's disease seems to be one of the more common causes from what I can find.

 

[Neuro]

Unusual I agree, but I know two people who have had bass loss suddenly occur, one recovered over time, the other not. One ear, not both.I don't know the mechanism but it is not the "normal" kind of hearing loss.

Virus is the most common answer patients receive, but rarely is a virus found.

 

[Prowler_88]

I'm not sure what your point here is. The preference for a bass bump is well documented in the research. Of course you don't need your speakers to do this, as a bass bump is easily (and better) achieved with any number of DSP systems.

Of course, the sort of bass your father's system has appears to be deeply unpleasant. I would have to wonder if he has some sort of hearing impairment.

Not much of a point. More of a chuckle at what can sometimes seem futile, when a lot of people seem to be very happy with substandard / totally non neutral or accurate images / sound etc.

 

[Salt]

Unusual I agree, but I know two people who have had bass loss suddenly occur, one recovered over time, the other not. One ear, not both.I don't know the mechanism but it is not the "normal" kind of hearing loss.

Bass, especially low bass, is transceived by bone to the inner ear, so it is usually the last frequency range you loose when outer and middle ear quits. If the inner ear quits, that would be a reason, but that means complete deafness.

 

[krabapple]

bown = bone, I presume

 

[Salt]

bown = bone, I presume

corrected the autocorrection

 

[Ellebob]

Meniere's disease and other conditions that affect the inner ear/vestibular cochlear nerve. Some medications cause hearing loss and those often cause low frequency hearing loss. Aspirin and other NSAIDs can cause it with higher doses and prolonged use. With those they typically resolve after stopping medications.
Certain diuretics (water pills) and chemo drugs tend to cause more permanent damage. While age related hearing loss typically affects high frequencies.