Sound Field Characterisation in Audio Reproduction with the Bit-Grouped Digital Transducer Array

摘要

A bit-grouped digital transducer array loudspeaker with different numbers of nominally identical transducers for each bit has been developed. The direct digital-to-acoustic conversion process produces a sound field whose quality is shown to be spatially dependent and highly influenced by real effects including non-uniform transducer frequency responses, transducer mismatching and baffle size. Spatial sound pressure and total harmonic distortion maps show that reducing the array size leads to improved reconstruction due to reduced phase distortion. For a given sampling rate and signal frequency, total harmonic distortion decreases as the listening distance is increased. A new criterion for the sweet-spot location in digital arrays is proposed based on the difference between the distortion introduced by path-length differences and the inherent quantisation distortion.