Re: [Jack-Devel] Network Audio Transmission - Quality

On Tue, Jun 25, 2013 at 02:59:10PM +0100, John Emmas wrote:
> Many years ago when I worked on AMS Neve's AudioFile DAW, our R&D guys  
> came up with a new design to improve the phase response of its  
> brick-wall filters, after countless complaints from BBC sound mixers.   
> Subtleties in phase are notoriously difficult to detect and the guys  
> were pretty confident that no-one would be able to hear the difference,  
> even though the phase response was measurably more linear - but I could  
> hear it.  In testing, I could tell with 100% reliability whether the old  
> filter or the new filter was being used.  The tests were (literally)  
> double-blind in the sense that I was forced to wear a blindfold AND to  
> wear headphones, so that I couldn't be influenced by knowing which  
> system was playing - nor by the direction or acoustic characteristics of  
> the sound coming from different loudspeakers.  What's interesting is  
> that out of an R&D dept of over 40 people, I was the only one who could  
> hear the difference!

And it was quite likely a difference in the level of some side effect like
pre-echo that you could hear, rather than the difference in phase response
itself. That's what makes it so hard to convince those that don't hear the
problem. The theory says something is inaudible, but they aren't looking
at what else is going on.

John

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