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Topic: audibility of polarity inversion (Read 43657 times) previous topic - next topic
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audibility of polarity inversion

Reply #25 –
Quote from: dantesan on
Polarity Inversion itself is only audible because of the physical limitations of the speakers to be able to mechanically move dynamically back and forth.
This is a plausible explanation of why we can hear a slight difference between a signal and its polarity inverted (negativesign-multiplied amplitude) version. But I favor opaqueice's explanation, that it is our ears that detect the difference, rather than the speaker drivers functioning asymmetrically. (the exact details of which are unknown or only partially known)

Both the speaker and the ear are transceivers...so asymmetry in the way they function could exist on both ends.

It does make sense that speaker cones and woofers would behave asymmetrically...however it's also been my personal experience that I cannot detect absolute (global) phase inversion on my midranges and woofers. I can only hear it (so far, and it's not been ABX'ed rigorously by me, although others have confirmed it here anyway) on my tweeters. Furthermore, all my tweeters are symmetric magnetic-planar "ribbon" style tweeters, with magnets on both sides (not the single sided kind like Magneplanars). Their operation ought to be symmetric.

Regarding the +/- signs and black/red wire issues, I have no idea either. Just do what opaqueice says, hook up your speakers consistently and you'll be fine.

I think you are supposed to put red (from amplifier) into red (on speaker)....and black into black. I have no idea which is + and which is -, though. But like I said before, I purposefully reverse-wire my 2-way speakers...so for those kinds of speakers I always put red into black.

audibility of polarity inversion

Reply #26 –
Both the speaker and the ear are transceivers...so asymmetry in the way they function could exist on both ends.

I think you mean transducers, but yes. Vibration is vibration. So it would follow that the ear would most likely function similarly.

audibility of polarity inversion

Reply #27 –
Both the speaker and the ear are transceivers...so asymmetry in the way they function could exist on both ends.

I think you mean transducers, but yes. Vibration is vibration. So it would follow that the ear would most likely function similarly.

audibility of polarity inversion

Reply #28 –
Quote from: dantesan on
Both the speaker and the ear are transceivers...so asymmetry in the way they function could exist on both ends.

I think you mean transducers, but yes. Vibration is vibration. So it would follow that the ear would most likely function similarly.


I think my little experiment with reversed headphones (described in the first post) has pretty much proven that the audibility of polarity inversion, at least with that test signal, is NOT due to asymmetry in the drivers, but rather to asymmetry in the way the ear/brain reacts to compression versus rarefaction.  Furthermore a mechanism for that is known - the hairs in the inner ear generate a voltage when perturbed by a sound wave, but not symmetrically.  A sine-wave sound gets converted more or less into a half-wave rectified version where the rarefaction part has been cut off.

So the question remains, is polarity audible in music?  If so, it may be hard to hear using ordinary commercial recordings because of these issues of mixing.  I'm going to experiment with some binaural and single mic recordings.

audibility of polarity inversion

Reply #29 –
Quote from: opaqueice on
Quote from: dantesan on

Both the speaker and the ear are transceivers...so asymmetry in the way they function could exist on both ends.

I think you mean transducers, but yes. Vibration is vibration. So it would follow that the ear would most likely function similarly.


I think my little experiment with reversed headphones (described in the first post) has pretty much proven that the audibility of polarity inversion, at least with that test signal, is NOT due to asymmetry in the drivers, but rather to asymmetry in the way the ear/brain reacts to compression versus rarefaction.  Furthermore a mechanism for that is known - the hairs in the inner ear generate a voltage when perturbed by a sound wave, but not symmetrically.  A sine-wave sound gets converted more or less into a half-wave rectified version where the rarefaction part has been cut off.

So the question remains, is polarity audible in music?  If so, it may be hard to hear using ordinary commercial recordings because of these issues of mixing.  I'm going to experiment with some binaural and single mic recordings.


I think you were actually conducting an experiment for "phase distortion". Generally speaking, when you add 2 different pure tones together with some delay in time for one of them, you can get a lot of combinations that may sound very alike (call it combined tone as to differentiate from pure tone). However, you may be surprised to see that these combined tones have very different wave forms when analysed with oscilloscope. People tend to ignore the phase differences and tend to extract the essence or idea from the frequency domain rather than the time domain. Generally, phase distortion is not critical until at times when the positive half is very different from the negative half of the combined tones(asymmetric). Actually, the hair cells are triggered by negative pressure (not positive) and send signals effectively with half-wave rectified manner. When you invert an asymmetric combined tones, you compare 2 tones with extreme difference with respect to the positve and negative halves. The A-B test for such instance would be very obvious. However at other random instances of this A-B test, people may report no big difference at all.

You may need a shortlist of references, but this link below would help you understand better:
A Primer on Phase Coherence