UMIK-X Microphone Array and REW Pro Version

[shauk_khan]

Hallo

We have recently brought the UMIK-X microphone array from miniDSP including the REW Pro version license. I have a question regarding performing a measurement.

The miniDSP user manual describes a multichannel measurement using REW, but that uses ASIO drivers and playing the signal from REW itself or from the measurement PC to the loudspeaker. Then it gives the option to have an rms average of the magnitude of all the channels captured. We want to have the same feature but our measurement setup and requirements is different as below

We want to perform the same measurement as above inside a car, but the measurement signal will be played externally (Pink Noise) from the car sound system. So my question is how can we do the setup to perform the measurement using the external signal and get the same results as above.

 

[markscohen]

That seems like a tall order. With an accurate pink noise source you would be able to characterize the frequency response amplitude of your car system, which is great, but unless you were able to precisely synchronize the timing of the noise source to the microphone recording, you would not be able to measure the phase response as a function of frequency.

When you have both amplitude and phase information for the system response, you can take the Fourier transform of those data to calculate the impulse response, which is the timing information used in REW, as best I understand it. However, without the phase information the impulse response is indeterminate.

Why can't you use the headphone port on the computer as an auxiliary input to the car stereo, instead of having a separate noise generator?

 

[finkaudio]

Hi Markscohen,

you obviously don't know what the array should do for us. The trick is to have the phase NOT in the measurement, So as we ignore the phase completely, we don't have to synchronize the noise. We have done those measurements with a "normal" microphone array in the past with SMAART, but thought it would be possible with REW pro as well.
And when did you buy your last new car? . They don't have AUX inputs any longer!

Best regards

KH

 

[markscohen]

My bad. Only hoping I could help.

 

[finkaudio]

....all good. Thanks for that

ATB KH

 

[John Mulcahy]

The RTA will show the average of the selected inputs. On Windows ASIO is required to access multichannel devices. Better playing back Pink PN than random pink. Questions like that are best posted on the REW forum, just chance that I came across this.

 

[thexder]

An amateur question.
May I ask where MultiChannel Mic Array can be helpful in home rooms?
So far I've been measuring one channel at the time ...

 

[MitchWolos]

I use the Umik-X for in car measurements. I have all 16 mics in a square configuration.

Most DSPs have a toslink input.

So, I use the Toslink output into the DSP.

Use the Pink Noise generator in REW.

For the most part. I measure each speaker separately. Then together. And I can see the summation between the two. Then I can try adjusting the delay or use an allpass filter.