12 巻 (2007) 4 号 p. 453-459
A pan-spatial dynamic virtual auditory display (Pan-spatial DVAD) has been developed, which can present virtual sound sources located at any position. The pan-spatial DVAD is an integrated system of the DVAD and an HRTF (Head-Related Transfer Function) calculation server. The DVAD detects the listener's head motion using a head tracking device and updates the HRTFs in response to the head motion. This enables a presentation of a highly realistic auditory space integrated with the listener's motor sensation. Our DVAD operates on Windows XP and its total system latency is about 50 ms, which is practically small enough for a localization experiment tool or actual applications. The HRTF calculation server numerically calculates HRTFs for sound sources located at any position around the head, based on the boundary element method. Via TCP/IP, the HRTF calculation server receives a source position in a relative coordinate system from DVAD system and quickly provides the corresponding HRTFs. The pan-spatial DVAD can present virtual sound sources located at any position since the HRTF calculation server provides the HRTF for every conceivable source position, whereas the conventional VADs and DVADs implementing an HRTF database can present only limited sound source positions due to a limited number of HRTFs.