Wikipedia
BRP-PACU
BRP-PACU is a dual channel FFT audio analysis tool. It is designed to be used with an omnidirectional calibrated microphone to configure any sound system with an appropriate equalization and delay. It compares the output of the system to the input of the system to obtain the transfer function of the system. These data allow one to perform final equalization using just the input/output of the DSP or any other device used for Equalization.