Sound image localization apparatus, stereophonic sound image enhancement apparatus, and sound image control system

• US 5,995,631 A
• Filed: 07/22/1997
• Issued: 11/30/1999
• Est. Priority Date: 07/23/1996
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Kawai Gakki Seisakusho
• Original Assignee: Kabushiki Kaisha Kawai Gakki Seisakusho
• Inventors: Fujita, Akihiro, Kamada, Kenji, Kuwano, Koji
• Primary Examiner(s): CHIN, VIVIAN C
• Application Number:
  US08/898,029
• Time in Patent Office: 861 Days
• Field of Search: 381/1, 381/17, 381/61, 381/63, 381/307, 381/309, 381/310
• US Class Current: 381/1
• CPC Class Codes: H04S 1/002 Non-adaptive circuits, e.g. manually adjustable or static, for enhancing the sound image or the spatial distribution control circuits for electronic adaptation of the sound field H04S7/30
• CPC Class Codes: H04S 1/005 For headphones

Abstract

A stereophonic sound image enhancement apparatus subtracts a right input signal from a left input signal and amplifies the subtracted signal to produce a difference signal, and also subtracts a right crosstalk signal from a left low-frequency-range enhanced signal obtained by filtering the left input signal. Then, the difference signal is added to this subtracted signal, and the added signal is outputted as a left output signal. Also, the left crosstalk signal is subtracted from a right low-frequency-range enhanced signal obtained by filtering the right input signal, and the difference signal is subtracted from the subtracted signal to output the subtraction result as a right output signal. Furthermore, a sound image control apparatus applies a left-channel head related transfer function to a monophonic input signal to output the resultant signal as a left input signal "Lin", and also applies a right-channel head related transfer function to this monophonic input signal "Min" to output the resultant signal as a right input signal "Rin". The sound image control apparatus performs a crosstalk canceling process operation with respect to these left input signal "Lin" and right input signal "Rin", and further mixes the left input signal "Lin" and the right input signal "Rin" with signals having phases reverse to those of the left/right input signals. Finally, the signals processed by the crosstalk canceling process and the mixing process are mixed with each other.

Claims

1. A stereophonic sound image enhancement apparatus comprising:

crosstalk canceling means for producing a first left signal formed by subtracting a right crosstalk signal from a left input signal, and a first right signal formed by subtracting a left crosstalk signal from a right input signal;

reverse-phase signal producing means for producing a second left signal formed by mixing a reverse-phase signal of the right input signal with the left input signal, and a second right signal formed by mixing a reverse-phase signal of the left input signal with the right input signal; and

mixing means for mixing the first left signal derived from said crosstalk canceling means with the second left signal derived from said reverse-phase signal producing means to produce a left output signal, and for mixing the first right signal derived from said crosstalk canceling means with the second right signal derived from said reverse-phase signal producing means to produce a right output signal,

wherein said crosstalk canceling means comprises left crosstalk signal producing means for producing the left crosstalk signal based on the left input signal;

right crosstalk signal producing means for producing the right crosstalk signal based on the right input signal;

a left-channel crosstalk calculator for subtracting the right crosstalk signal from the left input signal;

a first left-channel crosstalk filter for filtering a signal derived from said left-channel crosstalk calculator to produce the first left signal;

a right-channel crosstalk calculator for subtracting the left crosstalk signal from the right input signal; and

a first right-channel crosstalk filter for filtering a signal derived from said right-channel crosstalk calculator to product the first right signal.

2. The stereophonic sound image enhancement apparatus according to claim 1, wherein said left crosstalk signal producing means includes

a left-channel crosstalk attenuator for attenuating said left input signal;

a left-channel crosstalk delay device for delaying an output signal derived from said left-channel crosstalk attenuator; and

a second left-channel crosstalk filter for filtering an output signal derived from said left-channel crosstalk delay device to output said right crosstalk signal,

and wherein said right crosstalk signal producing means includes

a right-channel crosstalk attenuator for attenuating said right input signal;

a right-channel crosstalk delay device for delaying an output signal derived from said right-channel crosstalk attenuator; and

a second right-channel crosstalk filter for filtering an output signal derived from said right-channel crosstalk delay device to output said left crosstalk signal,

wherein a filter coefficient of said first left-channel crosstalk filter is determined based on a amplification coefficient of said right-channel crosstalk attenuator, a delay coefficient of said right-channel crosstalk delay device and a filter coefficient of said second right-channel crosstalk filter, and a filter coefficient of said first right-channel crosstalk filter is determined based on a amplification coefficient of said left-channel crosstalk attenuator, a delay coefficient of said left-channel crosstalk delay device and a filter coefficient of said second left-channel crosstalk filter.

3. The stereophonic sound image enhancement apparatus according to claim 1, wherein said reverse-phase signal producing means comprises:

a left-channel reverse-phase attenuator for attenuating the left input signal;

a left-channel reverse-phase delay device for delaying an output signal derived from said left-channel reverse-phase attenuator;

a right-channel reverse-phase attenuator for attenuator for attenuating the right input signal;

a right-channel reverse-phase delay device for delaying an output signal derived from said right-channel reverse-phase attenuator;

a left-channel reverse-phase calculator for subtracting the output signal derived from said right-channel reverse-phase delay device from the output signal derived from said left-channel reverse-phase attenuator to produce the second left signal; and

a right-channel reverse-phase calculator for subtracting the output signal derived from said left-channel reverse phase delay device from the output signal derived from said right-channel reverse-phase attenuator to produce the second right signal.

4. The stereophonic sound image enhancement apparatus according to claim 1, wherein said reverse-phase signal producing means comprises:

a left-channel reverse-phase attenuator for attenuating said left input signal by multiplying said left input signal by a gain "e";

a left-channel reverse-phase delay device for delaying an output signal from said left-channel reverse-phase attenuator;

a right-channel reverse-phase attenuator for attenuating said right input signal by multiplying said right input signal by a gain "e";

a right-channel reverse-phase delay device for delaying an output signal from said right-channel reverse-phase attenuator;

a left-channel reverse-phase calculator for mixing said left input signal, the output signal from said right-channel reverse-phase delay device and the output signal from said left-channel reverse-phase attenuator;

a right-channel reverse-phase calculator for mixing said right input signal, the output signal from said left-channel reverse-phase delay device and the output signal from said right-channel reverse-phase attenuator;

left-channel sound quality correcting means for adding a signal obtained by multiplying an output signal from said left-channel reverse-phase calculator by a gain (1-e) to another signal obtained by filtering the output signal from said left-channel reverse-phase calculator by way of a low-pass filter and by multiplying the filtered signal by the gain "e" to output this adding result as the second left signal; and

right-channel sound quality correcting means for adding a signal obtained by multiplying an output signal derived from said right-channel reverse-phase calculator by a gain (1-e) to another signal obtained by filtering the output signal from said right-channel reverse-phase calculator by way of a low-pass filter and by multiplying the filtered signal by the gain "e" to output this adding result as the right output signal.

5. The stereophonic sound image enhancement apparatus according to claim 1, further comprising:

head related transfer function applying means including left-channel head related transfer function applying means for applying a left-channel head related transfer function to a monophonic input signal to output the resultant signal as said left input signal, and right-channel head related transfer function applying means for applying a right-channel head related transfer function to said monophonic input signal to output the resultant signal as said right input signal.

6. The sound image control apparatus according to claim 5, further comprising:

direction instructing means for instructing a direction along which a sound image is moved,

wherein said head related transfer function applying means comprises;

first left-channel head related transfer function applying means for applying a left-channel head related transfer function corresponding to a first direction;

first right-channel head related transfer function applying means for applying a right-channel head related transfer function corresponding to said first direction;

second left-channel head related transfer function applying means for applying a left-channel head related transfer function corresponding to a second direction;

second right-channel head related transfer function applying means for applying a right-channel head related transfer function corresponding to said second direction;

first weighting means for applying a weighting factor "α

" to the respective signals derived from said first left-channel head related transfer function applying means and from said first right-channel head related transfer function applying means in response to the instruction issued from said direction instructing means;

second weighting means for applying a weighting factor "1-α

" to the respective signals derived from said second left-channel head related transfer function applying means and from said second right-channel head related transfer function applying means in response to the instruction issued from said direction instructing means;

left mixing means for mixing a signal derived from said first left-channel head related transfer function applying means to which the weighting factor "α

" has been applied by said first weighting means with another signal derived from said second left-channel head related transfer function applying means to which the weighting factor "1-α

" has been applied by said second weighting means to thereby produce the left input signal; and

right mixing means for mixing a signal derived from said first right-channel head related transfer function applying means to which the weighting factor "α

" has been applied by said first weighting means with another signal derived from said second right-channel head related transfer function applying means to which the weighting factor "1-α

" has been applied by said second weighting means to thereby produce the right input signal;

under which 0≦

α

≦

1.

7. The sound image control apparatus according to claim 5, further comprising:

direction instructing means for instructing a direction along which a sound image is moved,

wherein said head related transfer function applying means is constructed of;

first left-channel head related transfer function applying means for applying a left-channel head related transfer function corresponding to a first direction;

first right-channel head related transfer function applying means for applying a right-channel head related transfer function corresponding to said first direction;

second left-channel head related transfer function applying means for applying a left-channel head related transfer function corresponding to a second direction;

second right-channel head related transfer function applying means for applying a right-channel head related transfer function corresponding to said second direction;

first weighting means for applying a weighting factor "α

" to the respective signals derived from said first left-channel head related transfer function applying means and from said first right-channel head related transfer function applying means in response to the instruction issued from said direction instructing means;

second weighting means for applying a weighting factor "1-α

" to the respective signals derived from said second left-channel head related transfer function applying means and from said second right-channel head related transfer function applying means in response to the instruction issued from said direction instructing means;

left mixing means for mixing a signal derived from said first left-channel head related transfer function applying means to which the weighting factor "α

" has been applied by said first weighting means with another signal derived from said second left-channel head related transfer function applying means to which the weighting factor "1-α

" has been applied by said second weighting means to thereby produce the left input signal; and

right mixing means for mixing a signal derived from said first right-channel head related transfer function applying means to which the weighting factor "α

" has been applied by said first weighting means with another signal derived from said second right-channel head related transfer function applying means to which the weighting factor "1-α

" has been applied by said second weighting means to thereby produce the right input signal;

under which 0≦

α

≦

1.

8. The stereophonic sound image enhancement apparatus according to claim 5, wherein said reverse-phase signal producing means comprises:

a left-channel reverse-phase attenuator for attenuating the left input signal;

a left-channel reverse-phase delay device for delaying an output signal derived from said left-channel reverse-phase attenuator;

a right-channel reverse-phase attenuator for attenuating the right input signal;

a right-channel reverse-phase delay device for delaying an output signal derived from said right-channel reverse phase attenuator;

a left-channel reverse-phase calculator for subtracting an output signal derived from said right-channel delay device from the output signal derived from said left-channel reverse-phase attenuator to produce the second left signal; and

a right-channel reverse-phase calculator for subtracting an output signal derived from said left-channel delay device from the output signal derived from said right-channel reverse-phase attenuator to produce the second right signal.

9. The stereophonic sound image enhancement apparatus according to claim 8, further comprising:

direction instructing means for instructing a direction along which a sound image is moved,

wherein said head related transfer function applying means comprises;

first left-channel head related transfer function applying means for applying a left-channel head related transfer function corresponding to a first direction;

first right-channel head related transfer function applying means for applying a right-channel head related transfer function corresponding to said first direction;

second left-channel head related transfer function applying means for applying a left-channel head related transfer function corresponding to a second direction;

second right-channel head related transfer function applying means for applying a right-channel head related transfer function corresponding to said second direction;

first weighting means for applying a weighting factor "α

" to the respective signals derived from said first left-channel head related transfer function applying means and from said first right-channel head related transfer function applying means in response to the instruction issued from said direction instructing means;

second weighting means for applying a weighting factor "1-α

" to the respective signals derived from said second left-channel head related transfer function applying means and from said second right-channel head related transfer function applying means in response to the instruction issued from said direction instructing means;

left mixing means for mixing a signal derived from said first left-channel head related transfer function applying means to which the weighting factor "α

" has been applied by said first weighting means with another signal derived from said second left-channel head related transfer function applying means to which the weighting factor "1-α

" has been applied by said second weighting means to produce the left input signal; and

right mixing means for mixing a signal derived from said first right-channel head related transfer function applying means to which the weighting factor "α

" has been applied by said first weighting means with another signal derived from said second right-channel head related transfer function applying means to which the weighting factor "1-α

" has been applied by said second weighting means to produce the right input signal;

under which 0≦

α

≦

1.

10. A stereophonic sound image enhancement apparatus comprising:

crosstalk canceling means for producing a first left signal formed by subtracting a right crosstalk signal from a left input signal, and a first right signal formed by subtracting a left crosstalk signal from a right input signal;

reverse-phase signal producing means for producing a second left signal formed by mixing a reverse-phase signal of the right input signal with the left input signal, and a second right signal formed by mixing a reverse-phase signal of the left input signal with the right input signal;

mixing means for mixing the first left signal derived from said crosstalk canceling means with the second left signal derived from said reverse-phase signal producing means to produce a left output signal, and for mixing the first right signal derived from said crosstalk canceling means with the second right signal derived from said reverse-phase signal producing means to produce a right output signal,

head related transfer function applying means including left-channel head related transfer function applying means for applying a left-channel head related transfer function to a monophonic input signal to output the resultant signal as said left input signal, and right-channel head related transfer function applying means for applying a right-channel head related transfer function to said monophonic input signal to output the resultant signal as said right input signal;

direction instructing means for instructing a direction along which a sound image is moved,

wherein said head related transfer function applying means is comprises;

first left-channel head related transfer function applying means for applying a left-channel head related transfer function corresponding to a first direction;

first right-channel head related transfer function applying means for applying a right-channel head related transfer function corresponding to said first direction;

second left-channel head related transfer function applying means for applying a left-channel head related transfer function corresponding to said second direction;

second right-channel head related transfer function applying means for applying a right-channel head related transfer function corresponding to said second direction;

first weighting means for applying a weighting factor "α

" to the respective signals derived from said first left-channel head related transfer function applying means and from said first right-channel head related transfer function applying means in response to the instruction issued from said direction instructing means;

second weighting means for applying a weighting factor "1-α

" to the respective signals derived from said second left-channel head related transfer function applying means and from said second right-channel head related transfer function applying means in response to the instruction issued from said direction instructing means;

left mixing means for mixing a signal derived from said first left-channel head related transfer function applying means to which the weighting factor "α

" has been applied by said first weighting means with another signal derived from said second left-channel head related transfer function applying means to which the weighting factor "1-α

" has been applied by said second weighting means to produce the left input signal; and

right mixing means for mixing a signal derived from said first right-channel head related transfer function applying means to which the weighting factor "α

" has been applied by said first weighting means with another signal derived from said second right-channel head related transfer function applying means to which the weighting factor "1-α

" has been applied by said second weighting means to produce the right input signal;

under which 0≦

α

≦

1.

11. A stereophonic sound image enhancement apparatus comprising:

crosstalk canceling means for producing a first left signal formed by subtracting a right crosstalk signal from a left input signal, and a first right signal formed by subtracting a left crosstalk signal from a right input signal;

reverse-phase signal producing means for producing a second left signal formed by mixing a reverse-phase signal of the right input signal with the left input signal, and a second right signal formed by mixing a reverse-phase signal of the left input signal with the right input signal;

mixing means for mixing the first left signal derived from said crosstalk canceling means with the second left signal derived from said reverse-phase signal producing means to produce a left output signal, and for mixing the first right signal derived from said crosstalk canceling means with the second right signal derived from said reverse-phase signal producing means to produce a right output signal,

head related transfer function applying means including left-channel head related transfer function applying means for applying a left-channel head related transfer function to a monophonic input signal to output the resultant signal as said left input signal, and right-channel head related transfer function applying means for applying a right-channel head related transfer function to said monophonic input signal to output the resultant signal as said right input signal;

wherein said reverse-phase signal producing means comprises;

a left-channel reverse-phase attenuator for attenuating the left input signal;

a left-channel reverse-phase delay device for delaying an output signal derived from said left-channel reverse-phase attenuator;

a right-channel reverse-phase attenuator for attenuating the right input signal;

a right-channel reverse-phase delay device for delaying an output signal derived from said right-channel reverse-phase attenuator;

a left-channel reverse-phase calculator for subtracting an output signal derived from said right-channel delay device from the output signal dervied from said left-channel reverse-phase attenuator to produce the second left signal;

a right-channel reverse-phase calculator for subtracting an output signal derived from said left-channel delay device from the output signal derived from said right-channel reverse-phase attenuator to produce the second right signal;

direction instructing means for instructing a direction along which a sound image is moved,

wherein said head related transfer function applying means is comprises;

first left-channel head related transfer function applying means for applying a left-channel head related transfer function corresponding to a first direction;

first right-channel head related transfer function applying means for applying a right-channel head related transfer function corresponding to said first direction;

second left-channel head related transfer function applying means for applying a left-channel head related transfer function corresponding to said second direction;

second right-channel head related transfer function applying means for applying a right-channel head related transfer function corresponding to said second direction;

first weighting means for applying a weighting factor "α

" to the respective signals derived from said first left-channel head related transfer function applying means and from said first right-channel head related transfer function applying means in response to the instruction issued from said direction instructing means;

second weighting means for applying a weighting factor "1-α

" to the respective signals derived from said second left-channel head related transfer function applying means and from said second right-channel head related transfer function applying means in response to the instruction issued from said direction instructing means;

left mixing means for mixing a signal derived from said first left-channel head related transfer function applying means to which the weighting factor "α

" has been applied by said first weighting means with another signal derived from said second left-channel head related transfer function applying means to which the weighting factor "1-α

" has been applied by said second weighting means to produce the left input signal; and

right mixing means for mixing a signal derived from said first right-channel head related transfer function applying means to which the weighting factor "a" has been applied by said first weighting means with another signal derived from said second right-channel head related transfer function applying means to which the weighting factor "1-α

" has been applied by said second weighting means to produce the right input signal;

under which 0≦

α

≦

1.