hi all, I want to do get a rough idea of the acoustical impulse response of a room. This room is used by a choir and and I just want to get an idea how much the room influences timing and frequency accuracy.
To measure the room impulse response (RIR) and want to use a exponential swept sine. For that purpose I would like to know which frequency range should be used with regard to loudspeaker performance (e.g. freq. range of the loudspeaker), room size and singing frequency range. In addition I am interested in how short and long the sweep is allowed to be. If i want to do multiple swept sines in a row, how do i combine the IR in a way that does not add distortion in some way to the estimated IR. I have seen that there is an impulse response measurer, but i need to separate the audio recording from the IR extraction, because I do not have matlab available at that location.
I would do the following: use sweeptone to generate the sweep signal, then i play the sound in the mentioned room and record at the same time (and a bit longer of course) and then i would try to extract the IR using impzest. I tested that procedure in a small room with sweeps between 30Hz and 20kHz and durations of 2, 5, 10 and 20 seconds. the resulting RIRs from impzest had all different lengths and the length did not scale with the excitation signal (length was about .5, 1.6, 3.2 and 1.5s for sweep duration 2, 5, 10, 20s).
how could i combine RIRs from sines with different durations and/or multiple runs of a single sweep type. I also had a look into the RIR and the first noticable peak is at about 7.5ms, corresponding to 2.5m distance between loudspeaker and microphone. But the true distance is was about 1m. Can the bad loudspaker performance at 30Hz be the cause for that wrong value?
Many questions, i would be happy if someone could share some experience or answer a part of this question already. best regards