Time based room correction system for low frequencies using multiple loudspeakers

Improving sound from loudspeakers in a room is a big issue. We are facing a rather complicated and serious problem, as one can experience very big variations in sound pressure level - up to 30 dB - in a room, especially at low frequencies. An innovative way of looking at the problem in the time-domain by the construction of a finite-difference time-domain approximation program (FDTD) has lead to a novel and simple solution also working in the time-domain called Controlled Acoustically Bass System (CABS). Working in the time-domain CABS includes additional cancelling loudspeakers at the back wall in order to remove the back wall reflection. The system has first been simulated with surprisingly good results and later implemented maintaining good performance. CABS is able to give a homogeneous sound pressure level in the whole room at low frequencies. A DSP system consisting of both hardware and software has been made from scratch for further development of CABS.