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biscuits

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I could really use some help in order to understand how to obtain an impulse response from a frequency response.

I am dealing with acoustics, but my knowledge on the particular are basic.

I am trying to compare a theory for the scattering of sound from an object with measurements in an anechoic room. The theory gives me a formula of the sound pressure scattered from an object as a function of frequency. So I am making a simulation of this and I end up with complex pressure data and the corresponding frequencies. So I assume that is the frequency response of the system. If I am not mistaken, taking the inverse Fourier transform of those data would give me the Impulse Response of the system. Please correct me if I am wrong.

Then I am trying to compare these results with measurements in an anechoic chamber. I am using an MLS signal for excitation coming from a loudspeaker and I am recording with a microphone the pressure in front of the object. Now here I am getting confused. Is the FFT of the recorded signal the frequency response of the system? And how can I convert this into an Impulse Response? The FFT of the recorded signal does not look a lot like what I expected and taking the inverse FFT of the frequency response just gives me back the recorded signal. It does not look at all like an Impulse Response.

Could you please enlighten me, on what I am doing wrong and how I can correct it?

Thank you for your time