Re: [Jack-Devel] Network Audio Transmission - Quality
On 25 Jun 2013, at 20:51, John Rigg wrote:
> 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.
>
Exactly. Too many people believe that if the frequency response is adequate to cover the range of human hearing and the dynamic range is similarly adequate, that's enough - whereas in fact, things can be audible without them being related to either of those things. In this particular case the new filters gave a much more "defined" stereo image, instead of the slightly "muddy" image produced by our original filters. I found it so easy to detect that I was genuinely surprised at how few others could hear it.
John
1372221423.3129_0.ltw:2,a <95CBE8E7-B876-4546-96BA-E92C79547BF4 at tiscali dot co dot uk>