Radiation modes and loudspeaker arrays for close-listening: Experimental verification.

• Enhance the near filed of a loudspeaker array to realize personal audio systems for close-listening. • Spatial distributions and frequency characteristics of the acoustic pressure were investigated in the speech frequency band. • Robustness against a sphere the size of a human head was also investigated. In personal audio systems, the loudspeaker array for enhancing the near field is designed based on the theory of generalized radiation modes. These modes are formulated as a generalized eigenvalue problem associated with acoustic transfer functions on the surface of the loudspeaker array. The eigenvectors, i.e., the modal shapes, represent combinations of the amplitude and polarity of individual loudspeakers. The eigenvalues indicate the reactive-to-active ratio of the acoustic power generated by the loudspeaker array. Hence, the loudspeaker array is designed according to the eigenvector with the largest eigenvalue to maximize the reactive-to-active ratio. In this study, a planar array consisting of nine loudspeakers is constructed, and the acoustic radiation characteristics are experimentally investigated. [ABSTRACT FROM AUTHOR]