Can You Trust Your Ears? By Tom Nousaine

[watchnerd]

3 channels is rock-bottom MINIMUM for a front soundstage, with no envelopment or depth. Sorry, but that's been firmly established for going on a century now.

If I wanted to listen to stereo recordings (since they're the default content) with 3 channels, would the center channel simply be the same of the left and right?

Or do I need something that is natively 3 channel to get the desired effect?

 

[svart-hvitt]

Up to a point. Neutrino and gravity wave detection is pretty hard, even compared to studying humans.

Sure. However, it seems like the hardest sciences, once they’ve solved a complex problem (say building nukes), they are pretty good at replicating processes to the extent that they take the processes to an industrial stage (say the incredibly small computer transistors).

Audio related: I think Genelec has come a far way putting it all together in audio, but I observe many people are not in agreement on that one (quite a lot of people are openly «Genelec haters»...).

 

[watchnerd]

This is venturing a bit off-topic, but has anybody tried Meridian's trifield codec, which transforms 2 channel into 3 channel? The idea seems interesting, but I have no idea whether it works out or not.

Sounds interesting, but never even heard of it. Where / how is it implemented?

 

[watchnerd]

I am one of those heretics who believes that we hear past the room.

I get the impression sometimes that Toole is kinda-sorta in this camp and/or doesn't think enough listening tests have been done on room correction to know what is really right and important.

 

[Jakob1863]

If I wanted to listen to stereo recordings (since they're the default content) with 3 channels, would the center channel simply be the same of the left and right?

Or do I need something that is natively 3 channel to get the desired effect?

Of course ideally it would be better some genuine 3 channel stuff, but it is possible to convert 2 channel stereo to 2 channel stereo with center. Jim Bongiorno coined imo the term "trinaural" and offered a so called trinaural processor, but the matrix equations are quite simple to implement:

C = 0.5(Li+Ri)
Lo = Li - 0.5Ri
Ro = Ri - 0.5Li

Ri and Li are the original 2 channel signals while Lo and Ro are the newly generated after processing.

Edit: found the website with the AES-convention paper in our archive:
http://milestech.com/aesimpre.htm

 

[svart-hvitt]

I get the impression sometimes that Toole is kinda-sorta in this camp and/or doesn't think enough listening tests have been done on room correction to know what is really right and important.

Which begs the question if skepticism (toward room correction) is theory based, empirically based or based on absence of academic exposure and practical experience.

My speculation: Maybe lack of (research) funds is a factor as well? Remember, room correction is heavily software oriented and some parties regard themselves as either HW or SW oriented.

 

[watchnerd]

Audio related: I think Genelec has come a far way putting it all together in audio, but I observe many people are not in agreement on that one (quite a lot of people are openly «Genelec haters»...).

Putting it all together in what way?

Full disclosure: I respect Genelec, but I've never liked their monitors. I'm an ATC / Dynaudio guy.

 

[watchnerd]

one of "high enough standard", and one which is not

@fas42 we've been down this rat hole before. Until you can quantify what is "high enough standard" using data, this is nothing better than "I know it when I hear it", which makes it out of the bounds of science.

 

[watchnerd]

Of course ideally it would be better some genuine 3 channel stuff, but it is possible to convert 2 channel stereo to 2 channel stereo with center. Jim Bongiorno coined imo the term "trinaural" and offered a so called trinaural processor, but the matrix equations are quite simple to implement:

C = 0.5(Li+Ri)
Lo = Li - 0.5Ri
Ro = Ri - 0.5Li

Ri and Li are the original 2 channel signals while Lo and Ro are the newly generated after processing.

That looks really similar to what I recall of crossfeed matrixes used in some headphone amps (e.g. Phonitor X).

 

[Jakob1863]

Have you noticed my edit with the link to the milestech website? There is lot more information available....

 

[watchnerd]

Have you noticed my edit with the link to the milestech website? There is lot more information available....

Thanks for the extra edit.

 

[j_j]

Descriptions of course sounded like this was a no-brainer that someone would make use of it. I take it AT&T or some offshoot of it owns the rights, and sadly no one has made it available? Is there anything similar available or in the works somewhere?

Pretty much, at least until it was too late for it to matter.

 

[j_j]

If I wanted to listen to stereo recordings (since they're the default content) with 3 channels, would the center channel simply be the same of the left and right?

Or do I need something that is natively 3 channel to get the desired effect?

You need something that is not only native 3 channel, but also properly produced in combination with the L/R channels. You asked a very complicated question, sorry, and one I am not at liberty to offer at least one method for at the minute.

 

[j_j]

I get the impression sometimes that Toole is kinda-sorta in this camp and/or doesn't think enough listening tests have been done on room correction to know what is really right and important.

Well, we can hear past the playback room, sometimes. Not always. Again, complicated.

Room correction can help with this, but it can't fix excess storage in a room at lower frequencies.

Remember, if you have a bass node (where it disappears), that means your room STORES TOO MUCH ENERGY, not that it has no energy, and that the pressure (but not 3d Volume velocity) is at a zero at that point.

Adding more energy to a room that stores too much is not, and I hope it's evident, a good solution!

 

[j_j]

Of course ideally it would be better some genuine 3 channel stuff, but it is possible to convert 2 channel stereo to 2 channel stereo with center. Jim Bongiorno coined imo the term "trinaural" and offered a so called trinaural processor, but the matrix equations are quite simple to implement:

C = 0.5(Li+Ri)
Lo = Li - 0.5Ri
Ro = Ri - 0.5Li

Ri and Li are the original 2 channel signals while Lo and Ro are the newly generated after processing.

Edit: found the website with the AES-convention paper in our archive:
http://milestech.com/aesimpre.htm

This will fail to provide anything near the best results, because of the lack of time cues.

 

[amirm]

What JJ and I are talking about is ABX as a development tool. What developer uses to debug code with. Obviously, unless you are writing paper or course about detailed encoder development, you don't publish much about this. About as high as I've ever seen this sort of thing percolate is the paper from Apple a few years back about processing files for download on their music site.

You have no experience with how codecs are developed Arny. Only JJ and I do. JJ said he used ABX at AT&T together with other tools such as ABC/HR. I said that we never did including the time that JJ joined my team.

I also participated in a number of shoot outs conducted by others of lossy codecs and none used ABX. I also quoted a number of papers from AES, none of which showed ABX usage in that regard.

You are also wrong about lack of publishing. People doing signal processing work are the most anxious to write papers on just about everything they do. Certainly this is true of standardized codecs like MP3, AAC, AAC, Dolby AC-3, etc. Speaking of AC-3, here is another graph I have saved up in my library from an AES paper for another use:

We see again MOS style scoring of preference (from 0 to -4). No ABX, forced binary choice here.

The reason ABX is not used is because impairments are always audible enough to not worry about whether they exist at all for which ABX is used.

So please don't step outside of your expertise. When I comment on something i did professionally for a decade, it is not some random forum chatter to argue with using stuff you may have heard or assumed.

This is a science forum and you should expect higher level of knowledge here than you are assuming.

 

[Thomas savage]

@amirm ,
Chose your weapon..,

 

[watchnerd]

@amirm ,
Chose your weapon..,

View attachment 9443

I think you had some kind of error in your digital rendition of the analog visual color spectrum there -- those blacks don't appear to be as black as they should be.

Did you use a lossy image format?

 

[amirm]

If I wanted to listen to stereo recordings (since they're the default content) with 3 channels, would the center channel simply be the same of the left and right?

Or do I need something that is natively 3 channel to get the desired effect?

The ideal answer of course is a 3-channel recording that is done right (i.e. not stuff everything in the middle just the center channel). Seeing how that content is only available in multi-channel recordings and not vast amount of recorded music out there, you would want to play with 2-channel to 3-channel processor. Such a processor is sort of "smart" in that it extracts what it thinks should have been in center channel and pushes that there. The Lexicon Logic-7 is one such algorithm but there are others. To with, the inventor of that scheme, David Griesinger has written a very easy to read AES paper that describes what they did in the precursor to that:

Theoryand Designof a Digital Audio Signal Processor
for Home Use*
DAVID GRIESINGER
Lexicon, Waltham, MA 02154, USA

Hopefully you can find a copy of that without having to pay to get it on AES.

 

[amirm]

I think you had some kind of error in your digital rendition of the analog visual color spectrum there -- those blacks don't appear to be as black as they should be.

Did you use a lossy image format?

I don't think that accusation sticks at all. Thomas carries such purses everyday so is intimately familiar with how they look. His instagram page is full of such things.