Digital loudspeaker technology: current state and future developments

A digital loudspeaker produces a quantised sound field directly from a digital stimulus without a digital to analogue converter. Reproduction accuracy improves if the conversion is done as late as possible in the audio chain. This paper assesses the relative merits of the two currently competing technologies, digital transducer arrays and multiple voice coils, as well as possible alternatives, by considering the underlying principles. The requirements for crossovers and drive electronics are discussed, and the performance of prototype systems is reported. Methods to extend the present manufacturability to 16 bits include the use of semiconductor mass fabrication techniques in the case of arrays and applications of oversampling and noise shaping. In the latter case the psychoacoustic implications must be understood