Re: Impuls response toolbox

[Sergei Steshenko]

On Thursday, November 22, 2018, 3:41:49 PM GMT+2, Jan Vandendriessche <address@hidden> wrote:

Dear SIr,

You have very interesting software at “octave”.

I don’t have big knowledge about IR, so maybe you can point me in the good direction with my small question.

Can I measure an IR from a speaker with a small accelerometer on the cone (I have already done that). I want to measure the same speaker with a microphone. I want to have to have a new IR from the difference between the microphone IR and the accelerometer IR. So I can use the accelerometer to sound like the microphone captured signal.

Is this possible with one or more of the toolbox? And what we’ll be the steps?

 

Thank you.

 

Best regards,

Jan

 

 

Jan Vandendriessche

 

Erkend deskundige: Dr. ir. Filip J.R. Verbandt

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B-8000 Brugge

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First a dumb, but nominally correct answer to your "I want to have to have a new IR from the difference between the microphone IR and the accelerometer IR" question:

IR_difference = IR_accelerometer - IR_microphone;

where all three IRs are vectors of the same length and of the same organization, i.e. either column or row.

Now, regarding "So I can use the accelerometer to sound like the microphone captured signal" part suggests you want (rather, need) complex frequency responses and their ratio. For that start learning 'fft', 'ifft': https://octave.org/doc/v4.0.0/Signal-Processing.html .

The most difficult part which you do not address (and thus probably do not realize) is room acoustics. I.e. the accelerometer is mostly affected by the speaker cone movement while the microphone measure sound pressure produce by the speaker and by reflections from the walls, floor, ceiling and at all all objects present in the room.

You probably need to read https://en.wikipedia.org/wiki/Loudspeaker_measurement , https://www.researchgate.net/publication/2456363_Simultaneous_Measurement_of_Impulse_Response_and_Distortion_With_a_Swept-Sine_Technique .

--Sergei.