[HuoYuanJia]

I want to measure the the phase of some IEM. In fact, I have an item right here of which the designer said he made it phase-linear, but my IEC 60318-4 just shows a curve somewhat similar to the frequency response. It does so with most IEM but sometimes starts wrapping.
How would I know if my mic is even phase-linear? Or doesn't it even have to be? Or could I load a calibration to correct the mic's phase?

Thanks guys!

 

[castleofargh]

For the typical stuff like you would see on Innerfidelity(RIP), you won't get it with a mic, but by measuring the impedance+phase. You can find the schematic in the PDF for REW for the circuit you need(some wires a bunch of plugs, and one resistor that you can bypass or leave in).

For example, the phase(below) shown with the FR(above) measurement of my er4sr without any sort of correction(not even to fake a good raw) is like this:

But measuring the impedance(up, and phase below) I get this:

And Innerfidelity had this for the er4sr:

So if this is what you're after, impedance+phase is the measurement you want.

 

[HuoYuanJia]

Thank you! That's exactly what I was after. Cheers!

 

[HuoYuanJia]

Or maybe it isn't? I'm not searching for the electrical phase but acoustical phase, as shown here by Jerry Harvey:

 

[castleofargh]

Sorry, if what you care about is the phase measured with the FR, then I'm confidently ignorant. I only remember that for speaker measurements, we want remove the delay in the impulse, to only deal with the typical speaker phase thingy. So with REW maybe you can fool around with that and see if it gives you a more consistent (or expected) result. Not sure what's your level of handling REW, but I would open the pop up "overlay"(at the top and middle of the main window), show "phase" in that pop up. And use the main window to select "impulse"(because that's where you'll have more tools for the impulse). Looking at the impulse you go to "control" on the top right, and you have the "estimate IR delay" that will give you something close to what you should probably want(aligning the impulse with 0second). If that isn't satisfactory, you can always use the "t=0 offset" per sample for fine tuning. That might allow you to get a more realistic phase response, and probably will reduce the massive phase shifts, that you can wrap or not(basically instead of staying in a 360° system, the graph is allowed to wander out to infinity and beyond).
No w obviously all this would probably be much more interesting if you could find a reference somewhere(like a measurement of an IEM you also have, by somebody who really knows his stuff).

I do not know if there is a possibility to separate frequency response from phase shift itself... I don't even know how to say what I mean, not a great sign that I've mastered the subject ^_^. But talking about frequency response having an impact, if you apply some calibration/compensation to the graph, then you can expect it to also modify the phase graph. Maybe also something to check, although if the compensation is a legitimate one, then I imagine the result with it would also be more accurate. This is uneducated guess, I really don't know. I did read about all that long ago when trying to just learn everything about everything, but as soon as I found out that for a listener, frequency response mattered a lot and phase not so much, and often not at all, I just lost interest(yes I'm that lazy).

Now let's hope that somebody knowledgeable will come help you for real, and debunk half of what I just wrote.