Announcement. AES Presentation on “What is Accuracy” by our very own member @j_j_ or James D. (jj) Johnston - Chief Scientist - Immersion Networks

[antcollinet]

Thank you for sharing this opportunity to learn new stuff j_j_. We are very fortunate to host you as out Guest here.

Seconded.


EDIT: do we need to register to attend in order to watch the video later, or will the video be publicly accessible. it is at a rather unsociable 3:30am over here

 

[AdamG]

Seconded.


EDIT: do we need to register to attend in order to watch the video later, or will the video be publicly accessible. it is at a rather unsociable 3:30am over here

In post #13 j_j_ indicates that they should record the presentation and make it available for later viewing. While the linked page information seems to state that the presentation is free for all who wish to attend or Zoom. Going on that, it is possible that access to the recording for later consumption, will be free as well.

 

[j_j]

By "not even close" do you mean "inaccurate", "imprecise", or both?

Different issue.
First, one has to define accurate.

 

[j_j]

In post #13 j_j_ indicates that they should record the presentation and make it available for later viewing. While the linked page information seems to state that the presentation is free for all who wish to attend or Zoom. Going on that, it is possible that access to the recording for later consumption, will be free as well.

You must register to see the talk live, either in person or via zoom. Eventually (1 to 4 or so months) later the recording will be available. You do not need registration for that.

 

[voodooless]

Eventually (1 to 4 or so months) later the recording will be available

Make sure to post a link here if/when that happens!

 

[CapMan]

What Does "Accurate" Even Mean?

Perhaps 31th was deliberate in light of the title

 

[AdamG]

Perhaps 31th was deliberate in light of the title

I did not catch that typo. But ASR never lets an opportunity to correct someone go to waste.

 

[youngho]

There are number of talks by @j_j available on the website: https://www.aes.org/sections/pnw/jj.htm

I specifically recommend 2012 Soundfields vs human hearing (“For center images, the two signals from the loudspeakers conflict very badly. The interference creates frequency shaping that is the inverse of first-arrival distance cues and that mimics the effects of positive elevation cues“), the 2013 Heyser lecture (“What you like to listen to is PREFERENCE, not “accuracy”. You listen to what you prefer to hear, not what is measurably more accurate, unless of course, you prefer a good measurement. Preference is inviolate!” and “The SNR experiences teach the artistic side to ignore the engineer. The lack of DBT’s and testability teach the engineers to ignore the artist”), 2019 Hearing 096 (CNS: sound entering the ear, then loudness “integration,” feature analysis, and auditory object analysis, but last two affected by cognitive and other feedback like expectation), 2021 Mechanisms for spatial hearing (Direct sound includes nonlinear effects of air and some diffusion but arrives first. Auditory compression after 1 ms helps emphasize direct sound. Early reflected sound (longer path length up to ?4-5 m [up to 15 ms?]) reflect timbre of sound source, can affect timbre, localization, and width. Diffused reflections have leading edges somewhat scrambled, will add to loudness in most causes, may create sense of distance, will not usually mess up timbre. Late specular reflections generally bad, can garble articulation, creates echoes over ~50 ms delays, effectively create new leading edges. Reverberation tends to have less treble than direct sound. Diffuseness perception influenced by scrambled and different arrival time between ears across frequency. Distance perception: signal to reverb ratio, decorrelation of leading edge across frequency--more=distance). Parenthetical text not in quotes represents some degree of paraphrasing on my part.

Recordings of previous lectures can be found here (and in the case of the upcoming one will also presumably be found): https://www.aes-media.org/sections/pnw/pnwrecaps/

 

[CapMan]

I did not catch that typo. But ASR never lets an opportunity to correct someone go to waste.

Sorry - couldn’t resist. Tongue was firmly in cheek

 

[j_j]

Sign in is now open. Lots of seats left.

 

[Justdafactsmaam]

Sign in is now open. Lots of seats left.

Just signed up. Hopefully it won’t conflict with work. Really looking forward to this one. Great subject

 

[Justdafactsmaam]

There are number of talks by @j_j available on the website: https://www.aes.org/sections/pnw/jj.htm

I specifically recommend 2012 Soundfields vs human hearing (“For center images, the two signals from the loudspeakers conflict very badly. The interference creates frequency shaping that is the inverse of first-arrival distance cues and that mimics the effects of positive elevation cues“), the 2013 Heyser lecture (“What you like to listen to is PREFERENCE, not “accuracy”. You listen to what you prefer to hear, not what is measurably more accurate, unless of course, you prefer a good measurement. Preference is inviolate!” and “The SNR experiences teach the artistic side to ignore the engineer. The lack of DBT’s and testability teach the engineers to ignore the artist”), 2019 Hearing 096 (CNS: sound entering the ear, then loudness “integration,” feature analysis, and auditory object analysis, but last two affected by cognitive and other feedback like expectation), 2021 Mechanisms for spatial hearing (Direct sound includes nonlinear effects of air and some diffusion but arrives first. Auditory compression after 1 ms helps emphasize direct sound. Early reflected sound (longer path length up to ?4-5 m [up to 15 ms?]) reflect timbre of sound source, can affect timbre, localization, and width. Diffused reflections have leading edges somewhat scrambled, will add to loudness in most causes, may create sense of distance, will not usually mess up timbre. Late specular reflections generally bad, can garble articulation, creates echoes over ~50 ms delays, effectively create new leading edges. Reverberation tends to have less treble than direct sound. Diffuseness perception influenced by scrambled and different arrival time between ears across frequency. Distance perception: signal to reverb ratio, decorrelation of leading edge across frequency--more=distance). Parenthetical text not in quotes represents some degree of paraphrasing on my part.

Recordings of previous lectures can be found here (and in the case of the upcoming one will also presumably be found): https://www.aes-media.org/sections/pnw/pnwrecaps/

All great videos!

 

[j_j]

I'm wondering if anyone has any thoughts? Questions? Comments?

 

[Justdafactsmaam]

I'm wondering if anyone has any thoughts? Questions? Comments?

Comment: great presentation.

My quick summary of what I took away from it:

1. Preferences are inarguable
2. Preferences are inarguable
3. Stop arguing with people about what they like and stop demeaning them for it

4. Accuracy of an audio signal that goes through any wire, any active or passive circuitry, any ADC/DAC is relatively easy to thoroughly measure for accuracy.
5. It is easy because we have the source to directly compare it to
6. We can say with a great deal of confidence that there are thresholds of accuracy in these signals where we can claim audible transparency.
7. Speaker/rooms are not so easy to measure for accuracy.
8. Speaker/rooms are f#%king impossible to compare to an original acoustic event like a classical concert for accuracy
9. These things are difficult to measure because of lack of direct access to the source for direct comparison. Head transfer function and head movement
10. Traditional high end audio and audiophiles fail miserably to pay proper attention to the issues of head transfer functions and head movement.
11. The advancement of audio will need to address head transfer function and head movement
12. Speakers and rooms have to be considered as a system. The ideal design for one depends on the other.

So my question would be….did I understand everything? What am I getting wrong?

 

[j_j]

Comment: great presentation.

My quick summary of what I took away from it:

1. Preferences are inarguable
2. Preferences are inarguable
3. Stop arguing with people about what they like and stop demeaning them for it

4. Accuracy of an audio signal that goes through any wire, any active or passive circuitry, any ADC/DAC is relatively easy to thoroughly measure for accuracy.
5. It is easy because we have the source to directly compare it to
6. We can say with a great deal of confidence that there are thresholds of accuracy in these signals where we can claim audible transparency.
7. Speaker/rooms are not so easy to measure for accuracy.
8. Speaker/rooms are f#%king impossible to compare to an original acoustic event like a classical concert for accuracy
9. These things are difficult to measure because of lack of direct access to the source for direct comparison. Head transfer function and head movement
10. Traditional high end audio and audiophiles fail miserably to pay proper attention to the issues of head transfer functions and head movement.
11. The advancement of audio will need to address head transfer function and head movement
12. Speakers and rooms have to be considered as a system. The ideal design for one depends on the other.

So my question would be….did I understand everything? What am I getting wrong?

Seems about right! Point #1 and point #10 are the major ones. So many times, so many people.

#12 and I've given up on that.

 

[Justdafactsmaam]

I would love to see you do a lecture on concert hall acoustics. It’s such a tricky subject. Talk about bias effects! Utterly inescapable. The concert hall experience has so many non acoustic elements. The sight lines are a big one for me. I’m there to see the greatest musicians on the planet play the music as well as hear it. And the gravitas of the event, the spectacle of it. And the non repeatability of it!

But through all that there does seem to be some consistent sonic qualities we can attribute to each hall

 

[Justdafactsmaam]

I do have a question. In regards to measuring the accuracy of a stereo or multi channel playback system. Is there a set of metrics by which we can measure accuracy of the acoustic output from the listening position against the electrical signal of the source?

You did say there was something to using a binaural dummy head? But head movement or the lack there of was an issue?

But can we set aside head movement and measure for accuracy from a fixed listener head position?

And if so what utility do we get from such a measurement

Not to piss off any of the ASR regulars who pay close attention to the Toole and Olive research but it always seemed to me their advocation of early room reflections to enhance the subjective quality of the sound ran contrary to the assertion that greater accuracy always translated into higher subjective preference ratings. I don’t think there is a legitimate argument that early room reflections increase accuracy to the source since those reflections are not present in the source signal. And of course the preference either way is inarguable. But if one does prefer early reflections it follows that one is in turn preferring less accurate sound in that specific case.

 

[j_j]

I do have a question. In regards to measuring the accuracy of a stereo or multi channel playback system. Is there a set of metrics by which we can measure accuracy of the acoustic output from the listening position against the electrical signal of the source?

You did say there was something to using a binaural dummy head? But head movement or the lack there of was an issue?

But can we set aside head movement and measure for accuracy from a fixed listener head position?

And if so what utility do we get from such a measurement

Not to piss off any of the ASR regulars who pay close attention to the Toole and Olive research but it always seemed to me their advocation of early room reflections to enhance the subjective quality of the sound ran contrary to the assertion that greater accuracy always translated into higher subjective preference ratings. I don’t think there is a legitimate argument that early room reflections increase accuracy to the source since those reflections are not present in the source signal. And of course the preference either way is inarguable. But if one does prefer early reflections it follows that one is in turn preferring less accurate sound in that specific case.

When the talk comes out in the recorded form, watch the part about soundfield variables, etc. The answer is "kinda sorta" but what exactly can you measure? Pressure? Pressure plus velocity? At how many points, and how does that interact with your head?

 

[j_j]

Recording is available now there. Report will appear in a week, take or give, at www.aes.org/sections/pnw

 

[Justdafactsmaam]

Recording is available now there. Report will appear in a week, take or give, at www.aes.org/sections/pnw

I have a big question! I can’t believe I missed this on the live stream.

You talked briefly about measuring accuracy of DACs, amps and all things that handle an audio signal where we can directly compare the input to the output.

But then you dropped a couple bombs! You seemed to say that while there are thresholds of objective measurements that can tell us a component is unequivocally transparent the reality is such components that measure to that degree of accuracy are in the minority to a degree that would surprise many of us.

And you seemed to say that typical measurements are not a good measure of accuracy. Something to the effect that we should burn the paper they are written on?

I say “seemed” because I don’t want to misrepresent what you said.

But my questions! (Yeah more than one). My amps, DACs, processors, ADCs, am I believing incorrectly that as modern devices designed and built for transparency that they are achieving transparency? Or….that there may be audible colorations that I don’t know about?

How do we know? How do we find out? Can we do the proper measurements ourselves?

If I am incorrect about the transparency about my audio signal chain I want to know about it and I want to know how to correct it.