The radiation pattern of loudspeakers play a crucial role for how the acoustic power is distributed in the room. There is mounting evidence that early reflections from the side walls are beneficial, while early reflections parallel to the sagittal plane appears to be less desirable. Gradient loudspeakers provide a means of producing unidirectional radiation patterns. Moreover, their radiation patterns are frequency-independent. In view of these very desirable properties the characteristics of first-order gradient loudspeakers are analyzed. General expressions for sound pressure and particle velocity are derived and the distortion of the radiation patterns in the high-frequency region is reviewed.
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