Patent ID: 8295500

Claim:
A method for controlling directional sound sources based on a listening area, the method comprising: setting a listening area for receiving a first level of sound; setting a non-listening area for receiving a second level of sound lower than the first level of sound; selecting active sound sources to be used for sound output from among a plurality of sound sources; calculating a total sound energy of the active sound sources; calculating a total sound energy of the listening area; calculating a total sound energy of the non-listening area; calculating an optimal sound-source vector for minimizing a total sound energy of sound signals input to the active sound sources while maximizing a sound energy difference between the listening area and the non-listening area using values of the total sound energies of the listening area and the non-listening area; and controlling sound pressure and phase of the active sound sources depending on the optimal sound-source vector, wherein the total sound energy E L of the listening area L and the total sound energy E N of the non-listening area N are calculated according to the following equations: E L = 1 4 ⁢ ⁢ ρ ⁢ ⁢ c 2 ⁢ V l ⁢ ∫ V l ⁢ ( H k ⁢ s ) H ⁢ ( H k ⁢ s ) ⁢ ⁢ ⅆ V = 1 4 ⁢ ⁢ ρ ⁢ ⁢ c 2 ⁢ s H ( 1 V l ⁢ ∫ V l ⁢ H k H ⁢ H k ⁢ ⁢ ⅆ V ) ⁢ s = ⁢ 1 4 ⁢ ⁢ ρ ⁢ ⁢ c 2 ⁢ s H ⁢ R L ⁢ s E N = 1 4 ⁢ ⁢ ρ ⁢ ⁢ c 2 ⁢ V n ⁢ ∫ V n ⁢ ( G l ⁢ s ) H ⁢ ( G l ⁢ s ) ⁢ ⁢ ⅆ V = 1 4 ⁢ ⁢ ρ ⁢ ⁢ c 2 ⁢ s H ( 1 V n ⁢ ∫ V n ⁢ G l H ⁢ G l ⁢ ⁢ ⅆ V ) ⁢ s = ⁢ 1 4 ⁢ ⁢ ρ ⁢ ⁢ c 2 ⁢ s H ⁢ R N ⁢ s where ρ denotes density of a medium through which sound is propagated, c denotes a propagation speed of the sound, H denotes a Hermitian operator, V l denotes the volume of the listening area, V n denotes the volume of the non-listening area, H k denotes a transfer function between the sound source and the listening area, G l denotes a transfer function between the sound source and the non-listening area, S denotes a sound-source vector, R L denotes a correlation of sound pressures formed in the volume of the listening area V l by different sound sources, and R N denotes a correlation of sound pressures formed in the volume of the non-listening area V n by different sound sources.