Toshitaka Yamato

Apparatus for expanding and controlling sound fields

As in a compartment of an automotive vehicle, when a left- and a right-channel loudspeakers are disposed at angularly different positions from each other with respect to a frontward direction of a listening position, there will be formed a sound field laterally asymmetric with respect to the frontward direction of the listening position. In order to correct the asymmetry of the sound field, a crosstalk signal obtained by correcting the phase and the level of an acoustic signal of the left-channel from an acoustic signal source and a crosstalk adjustment signal obtained by correcting the level of the acoustic signal of the left-channel are fed to the right loudspeaker, or a center loudspeaker disposed between the left and right loudspeakers, together with an acoustic signal of the right-channel from the acoustic signal source. Similarly, a crosstalk signal obtained by correcting the phase and the level of an acoustic signal of the right-channel and a crosstalk adjustment signal obtained by correcting the level of the acoustic signal of the right-channel are fed to the left or center loudspeaker together with the acoustic signal of the left-channel from the acoustic signal source.

Mobile acoustic reproducing apparatus

A center loudspeaker is disposed near the middle between the left channel loudspeaker arranged at the front left side of the compartment and the right channel loudspeaker at the front right side, and this center loudspeaker transforms into a sound by the level-controlled signal of the sum of the acoustic signals of the right and left channels, and phase- and level-controlled signals of the acoustic signals of the right and left channels. As a result, the sound field is localized in the front of the listener, and right and left symmetrical wide-spread sound fields may be composed. Additionally, tweeters are disposed outside the right and left channel loudspeakers, and the mounting angles of the tweeters are adjusted so that the sounds released from the tweeters may be at an equal sound pressure level between the listener at the drivers seat and the listener at the front side seat. As a result, the drift of the sound field in the medium and high sound ranges may be eliminated in a simple structure, and right and left symmetrical wide-spread sound field are composed. Furthermore, corresponding to the opening or closing state of the window glass or seated position, by controlling the phase and level of the sounds released from the loudspeakers and the tweeters, sound fields always symmetrical to the listening position and spread widely may be composed.