Averaging energy of a multipoint measurement - possible? - Home Theater Forum and Systems - HomeTheaterShack.com

Old 03-19-14, 04:40 AM Thread Starter
Shackster

Join Date: Jan 2014
Location: Germany
Posts: 17
Averaging energy of a multipoint measurement - possible?

Hello everybody,

first of all I want to introduce myself as a german guy. So please excuse me if there are some mistakes in my writing ;-)

I'd like to make a multipoint-measurement for a studio listening seat/position. That means not only in one fixed microphone position, but in e.g. 30 points around the head/listening position in a range of 30-50cm left/right, forth/back, up/down. That will be done by moving the microphone by hand

My goal is to filter/EQ the speakers for the listening "area" because the head and seat position always varies in this area.

Therefore I will have to average the measurements, but not like in a fixed mic position. I'll have to average the energy without phase information.

Descirption from EASERA:

"Energy (Squared)
The amplitudes of the channels involved are energetically computed (i.e. the individual values are squared and summed, the result is divided by the number of channels (only for the Average mode), and then the square root is performed). The result has a phase angle of 0 and the imaginary part is therefore also 0 for all X-axis values.
This corresponds to an energetic addition, that does not consider the phase of the original data sets."

Can this be done with REW. And if so, how can i do it ? (As far as I serached through manual and programme I dont think so.)

Is it (at least) possible to have an automation for several (e.g. 30) measurements one after another with single .wav files in the end so I could compute it with Matlab or other tools?

and
best Regards
Sebastian
seppo85 is offline

Old 03-19-14, 08:57 AM
Senior Shackster

Join Date: Feb 2013
Location: Sydney AU
Posts: 134
Re: Averaging energy of a multipoint measurement - possible?

Hi there, I am not 100% certain but I think that if you go to the All SPL tab and click on the Average button, it will produce the average of the magnitude responses of the selected measurements. GIve it a try and report back?
HifiZine is offline
Old 03-19-14, 09:33 AM Thread Starter
Shackster

Join Date: Jan 2014
Location: Germany
Posts: 17
Re: Averaging energy of a multipoint measurement - possible?

Hi HifiZine,

It works/averages this way, but I dont know how its computed. After averaging there is no more Phase information so its not Complex.

I need to know whether its Magnitude(linear) or Energy(squared) averaged.

Descriptions from EASERA manual:
Magnitude (Linear)
The amplitudes of the channels involved are combined and if the Average mode was selected, then the result is divided by the number of channels. The result has a phase angle of 0 and the imaginary part is therefore also 0 for all X-axis values.
This corresponds to a coherent addition, that does not consider the phase of the original data sets.

Energy (Squared)
The amplitudes of the channels involved are energetically computed (i.e. the individual values are squared and summed, the result is divided by the number of channels (only for the Average mode), and then the square root is performed). The result has a phase angle of 0 and the imaginary part is therefore also 0 for all X-axis values.
This corresponds to an energetic addition, that does not consider the phase of the original data sets.

And it makes difference between the two. Not huge but big enough recognize
seppo85 is offline
Old 03-19-14, 05:23 PM
Senior Shackster

Join Date: Feb 2013
Location: Sydney AU
Posts: 134
Re: Averaging energy of a multipoint measurement - possible?

Oh I see. Can't give you a definitive answer but from a quick test (import one measurement twice, offset one by 40 dB, take average) it appears to be linear.

I'm struggling to understand why you need to do it that way... I guess it means that notches will have less effect on the result.... Hm... well I'll be interested to see what you come up with
HifiZine is offline

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