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I come from musical sciences, but I'm trying to learn something about acoustics, so here I am, asking for some help about the impedance tube sound absorption coefficient test.

I have and impedance tube, two microphones technique (ISO 10534-2), B&K microphones connected to the PULSE platform, and the ability to get the transfer function of the signals(H12). According to the referred ISO norm, I need to calculate the following equation in order to get the pressure reflection coefficient (R), and from there the absorption coefficient:

where: L is the distance from sample to the first mic, s the mics separation, k the wave number, f is frequency, and c is speed of sound

From the measurement platform, I can get two columns of numeric data from the transfer function of the two microphone signals(H12), (frequency and sound pressure), but now I don't know how to implement those values in the formula, as it has imaginary numbers. Should I import the air pressure values in real and imaginary form, or could I use the modulus as they come?

I've tried EXCEL, since it has some complex calculation capabilities, so I could make a sheet with the calculations and copy-past the values from the measurement platform to excel and get a graph, but I only get errors or unreal values. Should I use another software, like matlab or something?

I understand that the problem is my lack of knowledge in the adaption of mathematics to the realm of computers.. Unfortunately, I'm just starting to learn everything from scratch, mathematics included (I always get myself fascinated with everything I don't understand.. LOL ).

Could someone please give me some int into the good path?

Many thanks,

Isaac

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# Homework Help: Help on Sound Absorption Coefficient Calculation

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