Reproducing low-pitched signals through small loudspeakers

Ever since the invention of the electrodynamic loudspeaker there has been a need for greater acoustical output, especially at low frequencies. From a manufacturer's point of view it has been desirable for a long time to reduce the size of the loudspeaker (and cabinet). These two demands are physically contradictory. Options are being offered to evoke the illusion of a higher low-frequency response of the loudspeaker while the power radiated by the loudspeaker at those low frequencies remains the same, or is even lower. This is feasible by exploiting certain psychoacoustic phenomena. The required nonlinear signal processing is studied for a number of specific implementations. An elaborate analysis of the outcome of a listening test, aimed at assessing the subjective evaluation of the system presented, employing multidimensional scaling and biplots, is also presented.