[JohnM]

Hannes,

The impulse response is the time domain response of the room. Roughly speaking, it is obtained by taking the FFT of the captured sweep, dividing it by the FFT of the generated sweep and then taking the inverse FFT of the result. Once the impulse response has been generated you can generate frequency responses from it using whatever gate times you care to apply. You also have the option of using a long gate time and applying fractional octave smoothing to the frequency response itself.