Patent ID: 7917236
Filing Date: 2011-03-29
Classification: G10K,H04S

Abstract:
1. A virtual sound source reproducing device for carrying out signal processing of an input audio signal in accordance with impulse responses from a virtual sound source to both ears of a listener to localize a reproduced sound image at a position of the virtual sound source, the device comprising: head related transfer function processing means for carrying out signal processing of the input audio signal in accordance with a first initial portion along a time axis of the impulse responses contributing to perception by the listener of a position of the virtual sound source to obtain a pair of initial response signals, and for delaying the input audio signal by a time equivalent to a time length of the first initial portion of the impulse response to obtain a delayed output signal, the time length is in a range between 10 and 30 milliseconds; reflected sound processing means for processing the delayed output signal outputted by said head related transfer function processing means in accordance with a second predetermined portion along the time axis immediately after the first initial portion of the impulse response contributing to perception of only a distance to the virtual sound source to obtain a pair of reflected response signals; synthesizing means for respectively synthesizing the pair of initial response signals and the pair of reflected response signals to obtain a pair of synthesized audio signals; the head related transfer function processing means is comprised of an FIR type digital filter, and the FIR type digital filter is constituted, with cascade-connected delay elements being common elements, by a first FIR type digital filter for carrying out signal processing of the input audio signal in accordance with the first initial portion along the time axis of the impulse response from the virtual sound source to a left ear of the listener, said first initial portion contributing to the perception of a position of the virtual sound source, and a second FIR type digital filter for carrying out signal processing of the input audio signal in accordance with the first initial portion along the time axis of the impulse response from the virtual sound source to a right ear of the listener, and is supplied with the input audio signal to obtain the pair of initial response signals and the delayed output signal; and further comprising characteristic change means for detecting changes in position, respectively, of the left and right ears of the listener from initial states, respectively, of the left and right ears of the listener and for changing response characteristic of the head related transfer function processing means in response thereto such that the position of the virtual sound source is changed separately for the left and right ears of the listener in correspondence with the changes in position of the left and right ears of the listener from the respective initial states, in which at least a portion of the characteristic change means is worn by the listener during operation, wherein the characteristic change means comprises head portion rotational angle detecting means for detecting rotational angle speeds of both ears of the listener, displacement quantity calculating means for calculating position change quantities of the left and right ears of the listener from the respective initial states from an output of the head portion rotational angle detecting means indicating the rotational angle speeds, and characteristic control means for changing response characteristic of the head related transfer function processing means separately for the left and right ears of the listener in accordance with outputs of the displacement quantity calculating means respectively for the left and right ears of the listener.