Acoustic signal reproducing apparatus

An acoustic signal reproducing apparatus for use with headphone devices, comprising:

• a reference signal source for transmitting a reference signal for detecting an orientation of a listener's head,
• a pair of signal detection means arranged at respective positions on the listener's head for receiving the reference signal transmitted by said reference signal source,
• calculating means for calculating changes in orientation of the listener's head relative to an imaginary sound source on the basis of output signals from said pair of signal detection means and producing an output signal representing said changes in orientation,
• transmission characteristic processing means including a plurality of signal processing sections receiving input left and right channel acoustic signals and having preset impulse response coefficients indicative of transmission characteristics to each ear of the listener for providing a left channel and a right channel of input acoustic signals with predetermined transmission characteristics representing the location of said imaginary sound source relative to the listener's ears, said plurality of signal processing sections comprising
• a first signal processing section for subjecting the right channel of said input acoustic signals to a convolutional integration of an impulse response indicative of constant transmission characteristics to the right ear of the listener of the acoustic signals reproduced from the right channel of the input acoustic signals,
• a second signal processing section for subjecting the right channel of said input acoustic signals to a convolutional integration of an impulse response indicative of constant transmission characteristics to the left ear of the listener of the acoustic signals reproduced from the right channel of the input acoustic signals,
• a third signal processing section for subjecting the left channel of said input acoustic signals to a convolutional integration of an impulse response indicative of constant transmission characteristics to the right ear of the listener of the acoustic signals reproduced from the left channel of the input acoustic signals,
• a fourth signal processing section for subjecting the left channel of said input acoustic signals to a convolutional integration of an impulse response indicative of constant transmission characteristics to the left ear of the listener of the acoustic signals reproduced from the left channel of the input acoustic signals,
• first adder means for adding an output of said first signal processing section and an output of said third signal processing section and producing the left channel signal, and
• second adder means for adding an output of said second signal processing section to an output of said fourth signal processing section and producing the right channel signal, and
• acoustic signal processing means receiving the right and left channel signals output respectively from said first and second adder means of said transmission characteristic processing means for controlling the level and delay characteristics thereof in response to said output signal representing said changes in orientation from said calculating means,
• the input acoustic signals being reproduced by the headphone devices from outputs of said acoustic signal processing means.