Product directivity models for parametric loudspeakers

Abstract

In a recent work, the beamsteering characteristics of parametric loudspeakers were validated in an experiment. It was shown that based on the product directivity model, the locations and amplitudes of the mainlobe and grating lobes could be predicted within acceptable errors. However, the measured amplitudes of sidelobes have not been able to match the theoretical results accurately. In this paper, the original theories behind the product directivity model are revisited, and three modified product directivity models are proposed: (i) the advanced product directivity model, (ii) the exponential product directivity model, and (iii) the combined product directivity model. The proposed product directivity models take the radii of equivalent Gaussian sources into account and obtain better predictions of sidelobes for the difference frequency waves. From the comparison between measurement results and numerical solutions, all the proposed models outperform the original product directivity model in terms of selected sidelobe predictions by about 10 dB.

A convolution model for computing the far-field directivity of a parametric loudspeaker array

“…8 A modification to the product directivity model, namely, the advanced product directivity model, has been previously proposed. 16 Improved agreement between measured directivity and computed directivity has been observed particularly at directions near the first side lobes of the primary waves. However, overall accuracies of both product directivity models are not yet satisfactory.…”

Generating dual beams from a single steerable parametric loudspeaker

“…The theoretical basis of previous works is provided by the product directivity principle [23,24]. It implies that the directivity pattern of the DF can be roughly computed by the product of the directivity patterns of the PFs.…”

Modeling the directivity of parametric loudspeaker

“…Furthermore, the ultrasonic transducer array in the parametric loudspeaker is transformed into an equivalent Gaussian source array. Thus, the directivity of the difference frequency is predicated based on the advanced product directivity (APD) model [4]. The APD model accounts for the effective radii of the Gaussian sources to give a better prediction of the directivity of the difference frequency than the original product directivity principle.…”