REW phase interpretation and understanding

[Deleted member 48726]

In a measured system where all frequencies of the stimulus pass through the system with the same delay the phase plot will be flat.

Loopback measurement (wired output to input), 96 Khz SR, 48 Khz BW, 20 Hz - 24 KHz displayed, ≈ -12 dBFS, phase highlighted:

View attachment 242317

Ok. Shorted input/output causes the difference between signal to measured input to equal zero means it has no phase shift.

When difference occurs, which is inevitable when measuring in reality, a shift in phase occurs due to time delay?
The reason for the wrapped phases to be longer apart in low frequencies is because of the longer delays due to the larger soundwaves?
The more dampening in the room, the more the unwrapped phase will flatten and approach 0 °?

 

[sam_adams]

Ok. Shorted input/output causes the difference between signal to measured input to equal zero means it has no phase shift.

When difference occurs, which is inevitable when measuring in reality, a shift in phase occurs due to time delay?
The reason for the wrapped phases to be longer apart in low frequencies is because of the longer delays due to the larger soundwaves?
The more dampening in the room, the more the unwrapped phase will flatten and approach 0 °?

Here is another nearfield measurement of a ported subwoofer driver (tuned to about 26 Hz) using the Keele method linked above to remove—as much as possible—the room's influence on the measured response:

Where the plots for the phase and SPL cross on the graph has no bearing on either the frequency or phase response.

Here is the graph with the phase and SPL plots separated. SPL magnitude on the left and phase on the right. The frequency relationship remains the same.:

Try not to get hung up on the 'absolute phase' of the plot as the audibility of absolute phase is something that has been—and continues to be—debated.