I've never met a proof that phase was audible outside
Square waves can reveal HF (rise time) and LF (tilt) response cut offs, not to mention stability (overshoot and/or ringing, not to be confused with Gibbs). An easy quick check if you know what you are looking at.I can sometimes identify the sonic signature of a vintage piece of gear just by looking at the square wave response...usually by the amount of overshoot.
Indeed. I've heard the effects of shifting phase when it results in a change of spectrum because it triggers non-linearities, whether in teh electronics or the transducers or teh air or the ears..If a phase change results in a change in critical band stimulus it will be audible.
I'm not too convinced with this experiment.One easily accessible demonstration is at Purifi, who work on low distortion speaker driver designs. This page show the difference in audibility between phase modulation and amplitude modulation which result in an identical power spectrum of distortion, but which sound quite different:
https://purifi-audio.com/blog/tech-notes-1/doppler-distortion-vs-imd-7
The difference is very clear on my nearfields, I ignored the use headphones advice
I found that I got inconsistent results with nearfields, because surprisingly tiny differences in head position matter. Earbuds did the trick.
Could the fact that most recordings don't show symmetrical waveforms have anything to do with that?
I have a hard time imagining how speakers reproduce non-symmetrical waveforms. Especially since speakers must have a different response going one way compared to the other.
It's hard to measure, I presume, since all measurements are done with symmetrical waves.
It could also explain why open baffle speakers are popular with audio enthusiasts...
Am I right in assuming this box flipped polarity on both channels at a time?I'll prolly get royally flamed for this, but one of the most dramatic examples I heard of absolute phase in loudspeakers was when I had a phase switching box between my amp and speakers.
You are talking about "absolute polarity". I recall first writing about this in the 80s. I even put a polarity switch in one of my phono preamp designs because recordings, and consoles at the time were not strict about maintaining absolute polarity. Since then the industry has become more disciplined about preserving absolute polarity.I'll prolly get royally flamed for this, but one of the most dramatic examples I heard of absolute phase in loudspeakers was when I had a phase switching box between my amp and speakers. Playing Peter Gabriel's "Red Rain", the prominence of different elements of the dense mix was quite audibly different between the two positions of the phase switch box.
I think confirmation bias not at play here, because I had no expectation of the effect, and the balances were simply different; one didn't "sound better" than the other.
On simpler, less dense mixes and simpler-mic'd recordings, the difference was mostly that subtleties of the sound were more readily audible in one position or the other; and different for different recordings.
Could be that these effects were more audible because the speakers I was using were two-ways, using very fast, high quality drivers (Dynaudio) and phase-linear (first order) crossovers. More complex speakers/crossovers may blur/scramble these effects.
Yes, both L/R at the same time; I always understood that was the definition of 'absolute phase/polarity', as opposed to (L/R) relative polarity.Am I right in assuming this box flipped polarity on both channels at a time?
I have noticed a number of times that phenomenon. It was always traced down to the fact that loudspeakers have asymmetrical response. It is particularly sensible on bass units, where the diaphragm excursion is important. The main reason for that is that the induction varies differently in a direction than in the other.
Most loudspeakers are subject to that. Loudspeaker designers have tried since ages to reduce this phenomenon. This is the base for JBL's SFG (Symmetrical Field Geometry) or Purifi's Constant Force Factor.
There are other factors that result in asymmetrical response, surround radiation, air compression vs. deflation.
It's actually pretty common with many acoustic instruments.I only became aware that most audio is asymmetrical in nature a few years ago.
It's been a few decades since I wrote about this but as I recall not only are vocals percussive and asymmetrical but brass and horns are notoriously asymmetrical.It's actually pretty common with many acoustic instruments.
The easiest to generate asymmetric waveform is your own voice.
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