Patent ID: 6650758
Filing Date: 2003-11-18
Classification: H04R

Abstract:
A directional sound source comprising a dipole loudspeaker having two acoustic sources driven by two respective electrical drivers, an audio input connected to feed an audio signal to the two electrical drivers, a null direction control means connected to the audio input to introduce a phase difference into the audio signal fed to one of the two electrical drivers relative to the other of the two electrical drivers, a microphone for sensing acoustic signals from the dipole loudspeaker and locatable in a plane in which it is desired that acoustic signals at all audible frequencies from the dipole loudspeaker be minimum such that the sound is substantially inaudible and a feedback circuit interconnecting the microphone with the null direction control means such that the null direction control means adaptively introduces the phase difference until the acoustic signals at all audible frequencies sensed by the microphone are minimum.