JPH0946797A - Audio signal reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an audio signal reproducing device capable of obtaining a superior localization feeling outside the head by a listener hearing sound from a headphone by complementing the strength of the sound source direction discrimination capacity of a person by direction. SOLUTION: This device is the audio signal reproducing device to reproduce two systems of audio signals by the headphone 13, and it is provided with an angle detecting part 14 which detects the angle of rotation of the head of the listener of the headphone 13, and a signal processing part 11 which performs such control to move the orientation direction of the audio signal in a direction opposite to the angle of rotation, and the signal processing part 11 performs such control to move the orientation direction at angle change with a ratio larger than that of the change of angle of rotation when the listener faces the neighborhood of a front.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acoustic signal reproducing device for reproducing acoustic signals of two systems by headphones.

[0002]

2. Description of the Related Art Conventionally, headphones are often used to reproduce acoustic signals. Headphones are smaller, lighter, and less expensive than speakers, and have extremely high sound fidelity. However, when the listener wearing the headphones moves his / her head, the headphones also move with the head, so that the relative direction and position of the sound image in the listener do not change. That is, in sound reproduction using headphones, a sound field is formed in the listener's head, and thus the sound image cannot be localized at an absolute position that is unrelated to the listener's posture.

In order to compensate for this, it has been conventionally proposed to detect the rotation angle of the listener's head and control the sound image to move in the opposite direction by the same angle as the detected rotation angle. (JP-A-3-214899). By such control, the listener who hears the sound from the headphones can feel as if he or she is listening to the sound from the two left and right speakers arranged in front of the listener, and a natural presence can be obtained. .

[0004]

By the way, since the sound source direction discriminating ability of a human in headphone reproduction is the weakest in the front, when a sound image localized in the front is heard by the headphones, the listener feels the direction and distance of the sound image. It becomes difficult to feel the sound, and the listener often feels that the sound image is localized in the occipital region.

Therefore, according to the above-mentioned conventional technique, when a sound image localized in the front is heard with the head facing the front, the listener feels that the sound image is localized in the back of the head, which is excellent. There is a problem that it is not possible to obtain a proper out-of-head localization.

The present invention has been made in view of the above-mentioned problems, and by compensating the strength of the sound source direction discrimination ability of the human, the listener who hears the sound from the headphones obtains a good out-of-head localization feeling. It is an object of the present invention to provide a sound signal reproducing device capable of performing the above.

[0007]

An apparatus according to the invention of claim 1 is an acoustic signal reproducing apparatus for reproducing acoustic signals of two systems by headphones, and detects a rotation angle of a head of a listener of the headphones. And a signal processing unit that controls the localization direction of the acoustic signal to move in a direction opposite to the rotation angle according to the detected rotation angle. , For changes in the rotation angle when the listener is facing the vicinity of the front,
The orientation direction is controlled to move at a rate of change of the angle larger than that.

In the apparatus according to the second aspect of the present invention, the localization direction moves with a smaller angle change than the change of the rotation angle when the listener faces the vicinity of the back surface. To control it.

According to a third aspect of the invention, in the signal processing means, a coefficient F is set in correspondence with the rotation angle.
It consists of an IR filter. The localization direction is controlled so that the localization direction moves with a larger rate of change than the change in the rotation angle when the listener is facing the front direction. At
The localization control is performed at an angle larger than the angle at which the head is actually rotated, and the localization of the sound image can be obtained even in the vicinity of the front of the listener.

For example, when a sound image localized in the center of the front is heard, the listener can sense the correct localization of the sound image by rotating the head to the left or right or in any one direction and removing the localization of the sound image from the front. However, in such a case, the listener has the same effect as rotating the head more than actually rotating the head. You can feel the localization.

Further, when the listener is facing the vicinity of the back surface, even if the listener rotates his / her head, only the effect of rotating the head or less is produced.

[0012]

1 is a block diagram functionally showing an audio signal reproducing device 1 according to the present invention, FIG. 2 is a block diagram showing a hard circuit of the audio signal reproducing device 1, and FIG. 3 is an out-of-head rotation angle. FIG. 4 is a diagram showing an example of the relationship between θh and the emphasis angle θc.
Is a diagram showing another example of the relationship between the head rotation angle θh and the emphasis angle θc, and FIG. 5 is a diagram showing the relationship between the head and the head rotation angle θh.

In FIG. 1, an audio signal reproducing apparatus 1 includes a signal processing unit 11, an amplifier 12 (amplifiers 12a and 12b),
The headphone 13 and the angle detector 14 are included. The signal processing unit 11 includes a filter unit 21 and a coefficient setting unit 2
2, a coefficient table 23, and adders 24 and 25. The angle detector 14 includes an angular velocity sensor 28 and an angle calculator 29.
Consists of

Acoustic signal Li input to the left and right input terminals
After the sound image localization control is performed by the signal processing unit 11, n and Rin are amplified by the amplifier 12 and output as sound by the stereo headphones 13. At the center of the upper part of the headphone 13, the rotation angle of the head of the listener wearing the headphone 13 (hereinafter referred to as the head rotation angle) θ.
An angular velocity sensor 28 including a gyro sensor or the like is provided for detecting h.

Based on the output signal S1 of the angular velocity sensor 28, the angle calculator 29 calculates the head rotation angle θh. As shown in FIG. 5, the head rotation angle θh is set to 0 at a specific reference position of the listener's head, and the angle is set to be positive in the right direction, for example. The specific reference position of the head is, for example, an angular position toward the center of the speaker when sound is reproduced by the speaker, but an arbitrary angular position may be used as the reference position. For example, the angular position according to any posture, such as the posture most preferred by the listener, the relaxed posture, and the most popular posture, may be used as the reference position. Such a reference position is set such that it is set as the reference position when the headphones 13 are worn on the head, or the state of the head when the setting switch is pressed by the operation of the listener is set as the reference position. It can be configured to be set.

The filter unit 21 includes FIR / LL, FIR
It is composed of four FIR filters 21a to 21d of / LR, FIR / RL, FIR / RR. These four FIR filters 21a to 21d control the direction and position of the sound image by the acoustic signals Lin and Rin. Each coefficient H in the four FIR filters 21a to 21d is the head rotation angle θh.
Is a parameter indicating the transfer characteristic (impulse response) from the two speakers SPL, SPR arranged at the front left and right proper positions in the direction of 0 to the left and right ears.

That is, FIR / LL coefficients HLL, F
IR / LR coefficient HLR, FIR / RL coefficient HRL,
And FIR / RR coefficients HRR are coefficients for correction so that reproduction characteristics equivalent to those of a speaker are reproduced when reproduced by headphones.

Therefore, when the listener is facing the front, that is, when the head rotation angle θh is 0, the two speakers SPL, which are arranged in front of the front even though listening to the headphones 13, I feel like I'm listening from SPR. For example, when the sound image by the acoustic signals Lin and Rin is in the center of the two speakers SPL and SPR, the sound image is localized in the front front direction for the listener. By setting these coefficients H differently, the direction of the sound image can be controlled.

The coefficient setting unit 22 sets the coefficient H in the filter unit 21. All the coefficients H to be set are stored in the coefficient table 23, and the coefficient setting unit 22 uses the angle calculation unit 2
A predetermined coefficient H is read out from the coefficient table 23 by the signal S2 indicating the head rotation angle θh output from 9 and set in the four FIR filters 21a to 21d of the filter unit 21. At that time, angle conversion is performed so that the input head rotation angle θh becomes the emphasis angle θc shown in FIG.

That is, when the head rotation angle θh is input, the coefficient setting unit 22 filters the coefficient H so that the localization direction of the sound image moves in the opposite direction to the corresponding emphasis angle θc by the same angle. Set to 21. As a result, the sound image moves in a direction relatively opposite to the head in response to the rotation of the listener's head, and the absolute position of the sound image remains substantially constant despite the rotation of the head.

In FIG. 3, when the head rotation angle θh is in the vicinity of 0, that is, when the listener is facing the front, the change in the head rotation angle θh is larger than the change in the head rotation angle θh. Causes the emphasis angle θc to change. When the head rotation angle θh is in the vicinity of π, that is, when the listener faces the vicinity of the back surface, the emphasis angle θc changes at a smaller rate of change with respect to the change in the head rotation angle θh. .

Therefore, when the listener is looking in the vicinity of the front, the localization direction of the sound image is controlled to move at a rate of change that is larger than the change in the head rotation angle θh. When the person is facing the vicinity of the back surface, the localization direction of the sound image is controlled to move with a smaller rate of change in the head rotation angle θh. That is, when the listener is facing the vicinity of the front, if the listener rotates his / her head even a little, the same effect as if the listener rotates the head more than the angle is produced. When the listener is facing the back, the rotation of the listener's head produces only the same effect as rotation below that angle.

There are two control methods based on the emphasis angle θc shown in FIG. One is the coefficient table 2
Each coefficient H corresponding to the head rotation angle θh is stored in 3, and the coefficient setting unit 22 obtains the emphasis angle θc from the head rotation angle θh by a table or the like, and the coefficient H corresponding to the obtained emphasis angle θc. Is read from the coefficient table 23. The other is that the coefficient table 23 stores a coefficient H that enables control corresponding to the emphasis angle θc, and the coefficient setting unit 22 stores the coefficient H according to the input head rotation angle θh. This is the method of reading.

The coefficient table 23 stores the coefficient H corresponding to the head rotation angle θh or the emphasis angle θc.
The coefficient H is stored not for all angles but for each fixed angle range. For example, assuming that the angle range is 10 degrees, one FIR filter has 3 units per rotation (2π).
Six types of coefficients H are required.

The adder 24 includes FIR filters 21a and 21c.
Output from the FIR filter 21.
Add the outputs from b and d. As a result, localization-controlled left and right acoustic signals Ls and Rs are obtained. The acoustic signals Ls and Rs are amplified by the amplifier 12 and output as sound from the headphones 13.

As shown in FIG. 2, the acoustic signal reproducing device 1
Are AD converters 51 and 52 for AD-converting the input acoustic signals Lin and Rin, an input port 53 for inputting the head rotation angle θh, an acoustic signal Ls obtained by DA conversion of the localization-controlled acoustic signal, DA converter 5 for obtaining Rs
4, 55, a DSP core 56 for performing calculations of FIR filters, a ROM 57 in which coefficients H are stored as a table,
And hardware such as the data bus 58. All or part of them can be configured by one DSP element.

According to the audio signal reproducing device 1, even if the listener rotates his / her head, the absolute position of the sound image is almost constant and does not change, and the listener feels that the sound image is localized at the absolute position. Moreover, in the vicinity of the frontal direction where the sound source direction discrimination ability is weak, localization control is performed at an angle (emphasized angle θc) larger than the angle at which the head is actually rotated (head rotation angle θh). A sound image can be localized even near the front of the person.

In particular, when a sound image localized in the center of the front is heard, the listener slightly rotates the head to the left or right or in one direction to remove the localization of the sound image from the front so that the correct localization of the sound image is obtained. Although it may behave as if it were felt, in such a case, the listener has the same effect as rotating the head more than actually rotating the head, so that the listener can rotate the sound image by a slight angle. You can feel the correct localization of. That is, by converting the head rotation angle θh into the emphasis angle θc, a great effect is exhibited when the head is rotated slightly in the vicinity of the front. As a result, an out-of-head localization feeling can be obtained for almost all head rotation angles θh, and a more natural presence can be obtained.

Further, when the listener is facing the vicinity of the back surface, even if the listener rotates his / her head, only the effect of rotation less than that angle is produced. Therefore, when the headphones 13 are used, the sound source direction discrimination ability is high. The orientation control in the strong back direction becomes gentle.

Since the sound image localization control for the acoustic signals Lin and Rin is performed by setting the coefficient H in the FIR filters 21a to 21d, reliable control can be performed with a simple configuration.

FIG. 4 shows that the head rotation angle θh is π or (3π
/ 2), that is, an example in which the rate of change in the emphasis angle θc is small with respect to the change in the head rotation angle θh when the listener is facing sideways.

In the above-mentioned acoustic signal reproducing apparatus 1, conversion from the head rotation angle θh to the emphasis angle θc is performed as shown in FIG.
Alternatively, a switch for selecting one of FIG. 4 is provided,
Two modes may be selectively set by switching the switch. Further, a mode in which the conversion to the emphasis angle θc is not performed may be provided. The two-system acoustic signals Lin and Rin can be obtained from two-system sound sources, or can be obtained from a single sound source in a pseudo manner or by various signal processing. Others, audio signal reproducing device 1
The entire structure or the configuration of each part, the processing content, the processing timing, the mounting form, and the like can be appropriately changed in accordance with the gist of the present invention.

[0033]

According to the inventions of claims 1 to 3,
By supplementing the strength depending on the direction of the sound source direction discrimination ability of the human, a listener who hears the sound from the headphones can obtain a good out-of-head localization feeling.

According to the second aspect of the present invention, the localization control in the back direction, which has a strong sound source direction discrimination ability, becomes gentle. According to the invention of claim 3, reliable control can be performed with a simple configuration.

[Brief description of drawings]

FIG. 1 is a block diagram of an audio signal reproducing device according to the present invention.

FIG. 2 is a block diagram showing a hardware circuit of the audio signal reproducing device.

FIG. 3 is a diagram showing an example of a relationship between an out-of-head rotation angle θh and an emphasis angle θc.

FIG. 4 is a diagram showing another example of the relationship between the head rotation angle θh and the emphasis angle θc.

FIG. 5 is a diagram showing a relationship between a head and a head rotation angle θh.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Acoustic signal reproducing apparatus 11 Signal processing part (signal processing means) 13 Headphones 14 Angle detection part (angle detection means) 21a-d FIR filter Ls, Rs Acoustic signal

Claims (3)

[Claims] 1. An audio signal reproducing device for reproducing two systems of audio signals by headphones, comprising: angle detecting means for detecting a rotation angle of a head of a listener of the headphones; and an angle detecting means according to the detected rotation angles. A signal processing unit that controls the localization direction of the acoustic signal to move in a direction opposite to the rotation angle, and the signal processing unit is provided when the listener is facing the front vicinity. An acoustic signal reproducing apparatus, wherein the localization direction is controlled to move at a rate of change that is larger than the change of the rotation angle. 2. The signal processing means responds to a change in the rotation angle when the listener faces the vicinity of the back surface,
The acoustic signal reproducing device according to claim 1, wherein the localization direction is controlled to move with a smaller angle change. 3. The acoustic signal reproducing device according to claim 1, wherein the signal processing means is an FIR filter having a coefficient set corresponding to the rotation angle.