| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a local reproduction device which has little sound leakage so that it can be used in a large room without allowing other people in the room to hear the contents of the conversation. <P>SOLUTION: A local reproduction device comprises: two pairs of speaker arrays symmetrically arranged relative to a center point (original point) which is a reproduction control point; and digital filters corresponding to respective speakers of the speaker arrays. A digital filter coefficient corresponding to each speaker is determined as follows: a total value Σ<SP POS="POST">N</SP><SB POS="POST">i=1</SB>A<SB POS="POST">i</SB>of values A<SB POS="POST">1</SB>, ..., A<SB POS="POST">N</SB>, which are calculated by convolving the digital filter coefficient corresponding to each speaker with an approximate transmission function determined by a distance from each speaker to the reproduction control point in a time domain, becomes non-zero; and also, for each attenuation control point b<SB POS="POST">n</SB>, a total value Σ<SP POS="POST">N</SP><SB POS="POST">i=1</SB>B<SB POS="POST">p,i</SB>of values B<SB POS="POST">p,1</SB>, ..., B<SB POS="POST">p,N</SB>, which are calculated by multiplying the digital filter coefficient corresponding to each speaker by an approximate transmission function determined by a distance from each speaker to each attenuation control point b<SB POS="POST">n</SB>in a frequency domain, becomes smaller than the non-zero value Σ<SP POS="POST">N</SP><SB POS="POST">i=1</SB>A<SB POS="POST">i</SB>as each attenuation control point b<SB POS="POST">n</SB>goes further from the reproduction control point. <P>COPYRIGHT: (C)2012,JPO&INPIT |
