I am recently try to figure out the time selective response algorithm of soundcheck. I found:
- It uses a logarithmic sweep sine as a stimulus, x(t) for example, with unit of Volt.
- The excitation signal is sent to the sound card to achieve D / A conversion, and then sent to the speaker through the power amplifier. While the speaker plays the sound, the microphone collects the sound to obtain the signal y (t), the unit is Pa. Assuming the sensitivity of the microphone is s0 V/Pa, we can convert the unit of y(t) to Volt( same as x(t)), for example y1(t)=y(t)[Pa]*s0[V/Pa].
According to Farina's paper "Advancements in impulse response measurements by sine sweeps", firstly I calculate the inverse filter f(t)=Am*fliplr(x(t)), where Am is an amplitude modulation. Then I perform the deconvolution:
deconv=conv(y(t),f(t)), it should be unit-less.
However the de-convolved response in soundcheck has a unit of Pa/s, and is much smaller than the results I calculated, even though they have exactly the same shape.
can anybody give me some tips, thanks!