If it's the same signal, it's the same. The phase difference at every frequency is now 180° and you go from the two signals adding at every frequency to canceling at every frequency.
 
In general, when you flip the polarity of one signal you go from the signals adding at any given frequency to canceling at the same frequency and vice versa. 

tom1
maybe it's partly due to the umlaut, and my Germanic heritage but to me this Bapü makes more sense than the other 5 or 6 on the forum

That is because McBapu is NOT the real bapu.

I was duly honoured to find that since McQ could not log in he created a "temporary" login and the only name he could come up with was variation on theme.
 
But how the heck did he get an aviator?
 
Stan Dupp & The Jennifer Tillies could not get an aviator stick or uploaded to be used.
 

When you reverse the polarity you change to phase by 180 degrees compared to the previous phase. That is a change in the phase relationship. You may also change the intensity as Drew notes if the signal is not symmetrical and centered on the zero amplitude line.
 
Having the very same signal in practical terms means the signal is coming from the same source through the same transducer and then being split, or from symmetrically placed identical transducers. If the source is the same, but is being recorded from two different microphones, then the phase relationship can be changed because the time it takes for the sound to reach microphone A is not necessarily identical to the time to reach microphone B. That is the same as shifting one signal along the time line by the amount of the arrival time difference. That difference in the phase relationship is very unlikely to be a 180 degree shift of signal A relative to signal B. If, and only if, it were 180 degrees, then reversing the polarity of microphone A would put the signal from microphone B back into the same phase relationship.
 
 
http://www.moultonlabs.co...and_polarity_reversal/

drewfx1
If it's the same signal, it's the same. The phase difference at every frequency is now 180° and you go from the two signals adding at every frequency to canceling at every frequency.
 
In general, when you flip the polarity of one signal you go from the signals adding at any given frequency to canceling at the same frequency and vice versa. 

This takes me back to my original question.
 
Is it correct to say that flipping polarity changes the phase relationship by 180* if in fact no actual time shift has occurred? That's a sincere question not a wise crack reply.
 
With the scenario you describe of the signals cancelling each other out to null (or some DC offset); Is it just a common habit to attribute that with the term "phase cancellation". Is that indeed the specific and correct term to use? There are many circumstances of phase cancellation, or rather comb filtering, which results in the introduction of nulls and or peaks, but is the cancellation due to reversed polarity one of those examples, or is reversed polarity a special case, not at all associated with time shift, where the cancellation occurs simply due to the summation of symmetrically reflective values?
 
I appreciated the differentiation between the terms "phase shift" and "phase relationship". Now we have introduced the term "phase difference".
 
I'm slowly learning.
 
 
 
 
 
 

bapu
I was duly honoured to find that since McQ could not log in he created a "temporary" login and the only name he could come up with was variation on theme.
 
But how the heck did he get an aviator?
 
Stan Dupp & The Jennifer Tillies could not get an aviator stick or uploaded to be used.

I borrowed John's avatar when he wasn't looking.

Actually the whole concept of phase is more or less dependent on a regularly repeating signal. In that sense the model of displacing the signal along the time line is an analytical, not a literal requirement. If the signal repeats cycle after cycle to both the negative and positive side of the zero time then moving it 1/4 cycle to the positive represents the change in the phase. If you actually delay a real signal 1/4 cycle you will produce a 1/4 cycle gap after which the sequence will be 1/4 cycle out of phase. The phase can be mathematically manipulated with no real time involved then reconstructed by a synthesizer in real time with the same effect. That is how digital polarity change or true phase shifting is accomplished. 

mike_mccue

drewfx1
If it's the same signal, it's the same. The phase difference at every frequency is now 180° and you go from the two signals adding at every frequency to canceling at every frequency.
 
In general, when you flip the polarity of one signal you go from the signals adding at any given frequency to canceling at the same frequency and vice versa. 

 
This takes me back to my original question.
 
Is it correct to say that flipping polarity changes the phase relationship by 180* if in fact no actual time shift has occurred? That's a sincere question not a wise crack reply.
 

 
Yes, the phase relationship/difference changed by 180°. 
 

 
With the scenario you describe of the signals cancelling each other out to null (or some DC offset); Is it just a common habit to attribute that with the term "phase cancellation". Is that indeed the specific and correct term to use? There are many circumstances of phase cancellation, or rather comb filtering, which results in the introduction of nulls and or peaks, but is the cancellation due to reversed polarity one of those examples, or is reversed polarity a special case, not at all associated with time shift, where the cancellation occurs simply due to the summation of symmetrically reflective values?

 
Phase cancellation is correct in my eyes.
 

I appreciated the differentiation between the terms "phase shift" and "phase relationship". Now we have introduced the term "phase difference".
 

Unfortunately, sometimes they are used interchangeably. :)

drewfx1

mike_mccue

drewfx1
If it's the same signal, it's the same. The phase difference at every frequency is now 180° and you go from the two signals adding at every frequency to canceling at every frequency.
 
In general, when you flip the polarity of one signal you go from the signals adding at any given frequency to canceling at the same frequency and vice versa. 

 
This takes me back to my original question.
 
Is it correct to say that flipping polarity changes the phase relationship by 180* if in fact no actual time shift has occurred? That's a sincere question not a wise crack reply.
 

 
Yes, the phase relationship/difference changed by 180°. 
 

 
With the scenario you describe of the signals cancelling each other out to null (or some DC offset); Is it just a common habit to attribute that with the term "phase cancellation". Is that indeed the specific and correct term to use? There are many circumstances of phase cancellation, or rather comb filtering, which results in the introduction of nulls and or peaks, but is the cancellation due to reversed polarity one of those examples, or is reversed polarity a special case, not at all associated with time shift, where the cancellation occurs simply due to the summation of symmetrically reflective values?

 
Phase cancellation is correct in my eyes.
 

I appreciated the differentiation between the terms "phase shift" and "phase relationship". Now we have introduced the term "phase difference".
 

Unfortunately, sometimes they are used interchangeably. :)

 
Thanks for sharing your thoughts.
 
I am gathering that the best way to think about this is to scrupulously avoid mixing up the term Phase Shift with the terms Phase Relationship or Phase Difference. Yes? Maybe?

Thanks for adding your comments David!