A virtual loudspeaker is a means to give an auditory illusion of which the listener perceives as an emanating sound source in space where actual loudspeaker does not exists at that point. A virtual loudspeaker located inside of a listening region is called a virtual-source-inside or a focused source. The virtual source inside can give an auditory scene to a listener that a very close sound is coming from in front of the array. This auditory effect can combined with current 3D visual contents and provide presense and reality of multimedia contents.
Generation of a virtual source inside cannot avoid the physical artifact due to causality, the listener always perceives pre-arriving sound before the desired sound comes. The human hearing system is very sensitive to a preceding waves, therfore this artifact can lead a listener to perceive the virtual source in undesired direction and the performance of the virtual source be severely damaged.
The pre-arriving artifact is called the pre-echo, and known to be very dependent on the listening position. In order to guarantee the effectiveness of the virtual source, there should be a method that can measure a performance of a virtual source.
In this thesis, cause and effect of the pre-echo for generating a virtual source inside is studied. The cause of the pre-echo is derived from Kirchhoff-Helmholtz integral equation and mathematically analyzed for limited case. The effect of the pre-echo is focused on the localization error, quantifying the angle difference between the desired direction and the perceived one. To quatify the localization performance of the system, a simple model which is known as an energy vector model is used. To separate the small localization error with masking phenomenon due to the precedence effect, masking suppression condition was defined and used with localization error measure.
Combining the suppression condition and the localization error, for given criterions, sweet spot for various cases c...