JP2893780B2 - Sound signal reproduction device - Google Patents

Description

The present invention relates to an audio signal reproducing apparatus for reproducing an audio signal by a headphone device.

B. Summary of the Invention In the present invention, transfer characteristic information indicating a transfer characteristic from a virtual sound source to a listener's both ears in only one quadrant of a rotational angle position of a listener's head is stored in storage means, Based on the transfer characteristic information of only one quadrant stored in the means, the transfer characteristic information at the head rotation angle position indicated by the detection output by the detection means for detecting the rotation angle position corresponding to the listener's head movement Is formed, and the audio signal processing unit processes the left channel and right channel audio signals, respectively, so that appropriate binaural reproduction for the virtual sound source can be performed.

C Prior Art Conventionally, a pair of headphone units supported in the vicinity of both auricles by being mounted on a listener's head by using a pair of headphone units, such as a headphone device that reproduces an acoustic signal by a headphone unit, is conventionally used. A binaural method is known as a method for improving the sense of direction and out-of-head localization of a sound image when reproducing an audio signal.

An audio reproduction system employing this binaural system is, for example, as described in Japanese Patent Publication No. 53-283, which performs predetermined signal processing on an audio signal reproduced by a headphone device. .

Here, the sense of direction of the sound image, the sense of localization outside the head, and the like are determined by the volume difference, time difference, phase difference, and the like of the sounds heard by the left ear and the right ear.

The signal processing is, for example, when sound reproduction is performed by a speaker device arranged apart from the listener, the distance between the sound source, that is, the speaker device, and the left and right ears of the listener is different and in the vicinity of the listener's head. This is a signal processing to make an acoustic effect equal to an acoustic effect caused by reflection, diffraction, etc. of the sound in an acoustic output reproduced by the headphone device. Such signal processing is performed by, for example, a process of convolving and integrating an impulse response corresponding to the above-described acoustic effect into the acoustic signals for the left ear and the right ear.

By the way, when sound reproduction is performed by a speaker device arranged at a distance from the listener, the absolute position of the sound image does not change even if the listener moves or rotates the direction of the head. Changes the relative direction and position of the sound image felt by the user. On the other hand, when sound reproduction is performed by the binaural method using the headphone device, when the listener turns the head, the headphone device is also rotated together with the head. The general direction and position do not change.

When binaural reproduction is performed using the headphone device in this manner, a sound field is formed in the listener's head due to the difference in the displacement state of the sound image with respect to the direction change of the listener's head, and the sound image is formed. It is difficult to localize the sound in front of the listener, and the sound image in front of the sound tends to rise.

Therefore, conventionally, Japanese Patent Application Laid-Open No. 42-227 and Japanese Patent Publication No. 54-192
As described in Japanese Patent Publication No. 42, by detecting a change in the direction of the listener's head and changing the state of the signal processing based on the detection result, a good frontal orientation can be obtained in the headphone device. There has been proposed an audio signal reproduction system adapted to be used. In such an audio signal reproducing system, a direction detecting device such as a so-called gyrocompass or magnetic needle is provided on the head of the listener. Then, based on the detection result of the direction detection device, the level adjustment circuit and the delay circuit for processing the audio signal are controlled so as to control the same sound as that of the sound reproduction by the speaker device placed away from the listener. They try to get a feeling of presence.

D Problems to be Solved by the Invention Meanwhile, in a conventional binaural reproduction system in which a headphone device is provided with a direction detection device using a gyro compass or the like as described above, signal processing is performed on an audio signal in accordance with a change in direction of a listener's head. , A good sound image localization feeling can be obtained.

However, in order to control the content of the signal processing performed on the acoustic signal according to the change in the direction of the listener's head, the impulse response corresponding to the acoustic effect given to the acoustic signal for the left ear and the right ear, that is, the transfer characteristic Is measured in advance for each predetermined angle, and the transfer characteristic information of the enormous amount of information is stored in the storage means, and is read out from the storage means in accordance with a change in the direction of the head, and necessary convolution integration processing is performed. Signals need to be applied in real time.

Accordingly, the present invention has been made in view of the above-described conventional circumstances, and aims to reduce the information amount of transfer characteristic information from a virtual sound source necessary for performing binaural reproduction of an acoustic signal by a headphone device to a listener's ear, With a simple configuration using a storage means having a small storage capacity, even when a listener moves, a sound that can perform a binaural reproduction that can obtain an extremely natural sound image localization feeling without moving a virtual sound source position by a headphone device. It is an object to provide a signal reproducing device.

E Means for Solving the Problems In order to achieve the above object, an audio signal reproducing device according to the present invention includes: a detecting unit that detects a rotation angle position according to a movement of a listener's head; Storage means for storing transfer characteristic information indicating transfer characteristics from the virtual sound source to the listener's both ears in only one quadrant of the rotational angle position of the head; and transfer characteristic information for only one quadrant stored in the storage means Sound signal processing means for forming transfer characteristic information at the head rotation angle position indicated by the detection output by the detection means, and processing left and right channel sound signals, respectively, An audio signal reproducing device for reproducing an audio signal through a processing means by a headphone device.

F Function In the acoustic signal reproducing apparatus according to the present invention, the storage means stores transfer characteristic information indicating a transfer characteristic from the virtual sound source to the listener's both ears in only one quadrant of the rotational angle position of the listener's head. Keep it. And the acoustic signal processing means,
The transmission characteristic information at the head rotation angle position indicated by the detection output by the detection unit that detects the rotation angle position according to the movement of the listener's head is converted to the transmission characteristic information of only one quadrant stored in the storage unit. The sound signal of the left channel and the sound signal of the right channel are processed based on the sound signal, and the processed sound signal is supplied to the headphone device.

G Example Hereinafter, an example of an audio signal reproducing device according to the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, a sound signal reproducing device according to the present invention is mounted on a head (M) of a listener by a headband (1) and a pair of the sound signal reproducing devices are provided near the right and left auricles of the listener. A headphone device (10) adapted to support the headphone units (2L) and (2R).

The headband (1) of the headphone device (10)
Has two sliders (4L) and (4R) slidably mounted with the support arms (3L) and (3R) protruding therefrom.
A pair of signal detectors (5L) and (5R) that sense a reference signal for position detection sent from the reference signal source (11) are provided at the distal ends of the support arms (3L) and (3R). . That is, the pair of signal detectors (5L) and (5R) are supported by sliders (4L) slidably mounted on the headband (1) and support arms (3L) formed to protrude from (4R).
(3R), the headband (1) and a pair of headphone units (2L),
(2R), that is, supported by the support arms (3L) and (3R) at a position separated from the headphone body.

In this embodiment, the reference signal source (11) is an ultrasonic signal source (12) and an ultrasonic speaker (13) for transmitting an ultrasonic signal from the ultrasonic signal source (12) as a reference signal.
It is composed of An ultrasonic microphone is used for each of the pair of signal detectors (5L) and (5R) that sense the reference signal.

As shown in FIG. 2A, the ultrasonic wave transmitted from the ultrasonic speaker (13), that is, the reference signal for position detection, is an ultrasonic wave of a predetermined level intermittently transmitted at predetermined time intervals. An ultrasonic wave whose phase can be detected, such as a burst wave or a so-called level-modulated wave whose level fluctuates at a predetermined cycle.

The pair of signal detectors (5L) and (5R) provided in the headphone device (10) are connected to the ultrasonic speaker (13).
2B and C of FIG. 2 having a time delay corresponding to the relative positional relationship between the listener and the ultrasonic speaker (13) after sensing the reference signal for position detection using the ultrasonic wave transmitted from the Each detection signal as shown is output.

The pair of signal detectors (5L) and (5R) are a slider (4L) slidably mounted on the headband (1),
The headband (1) and the pair of headphone units (2L) and (2R), ie, the headphone body, are provided at the distal ends of the support arms (3L) and (3R) projecting from (4R). The head is supported by the support arms (3L) and (3R) at a position away from the headphone body, with the head mounted, so that even if the listener moves or turns his head, It is possible to detect the ultrasonic wave transmitted from the ultrasonic speaker (13) extremely well without being behind the head, and to stably and accurately detect the reference signal for position detection. The pair of signal detectors (5L) and (5R) slide the sliders (4L) and (4R) along the headband (1) to detect the reference signal for position detection. Can be adjusted to the optimal position. For example, the headphone unit (2L), which is mounted on the head (M) of the listener by the headband (1) and supported in the vicinity of the right and left auricles of the listener,
Since the position of (2R) depends on the shape and size of the listener's head (M) and varies from person to person, the pair of the pair of headphone units (2L) and (2R) correspond to the positions of the headphone units (2L) and (2R). Adjust the positions of the signal detectors (5L) and (5R).

Each detection signal obtained by these signal detectors (5L) and (5R) is supplied to the arithmetic unit (14).

The arithmetic unit (14) is provided with first and second edge detection circuits (15), (5) to which detection signals of the reference signal for position detection by the signal detectors (5L) and (5R) are supplied. 16)
And a third edge detection circuit (17) to which an ultrasonic signal from the ultrasonic signal source (12), that is, the reference signal for position detection is supplied.

The first and second edge detection circuits (15) and (16)
Detects each rising edge of each detection signal by each of the signal detectors (5L) and (5R) and outputs each pulse signal as shown in D and E in FIG. 2 corresponding to the rising edge. . The first and second edge detection circuits (1
Each pulse signal obtained by 5) and (16) is supplied to a distance calculation circuit (18) and a binaural time difference detection circuit (19). Further, the third edge detection circuit (17) detects a rising edge of the ultrasonic signal from the ultrasonic signal source (12), and detects the rising edge as shown in FIG. 2F corresponding to the rising edge. Outputs a pulse signal. The pulse signal obtained by the third edge detection circuit (17) is supplied to the distance calculation circuit (18).

In the distance calculating circuit (18), said third pulse signal obtained by the edge detection circuit (17) and said first pulse signal obtained by the edge detection circuit (15) indicated by [Delta] T ₁ in Figure 2 a time difference t ₁ between the corresponding pulse, the third pulse signal obtained by the edge detection circuit (17) and said second pulse signal obtained by the edge detection circuit (16) indicated by [Delta] t ₂ in Figure 2 Time difference between corresponding pulses at
t ₂ is detected. Then, based on the respective time differences t _1, t ₂ and the sound velocity V, indicated by an arrow l ₀ in FIG. 3, the distance between the center of the ultrasonic speaker (13) and the listener's head (M)
Calculate l ₀ .

The sound speed V may be set in advance in the distance calculation circuit (18) as a constant.
It may be changed in accordance with a change in the atmospheric pressure or the like. The distance l is calculated based on the positional relationship between the signal detectors (5L) and (5R) and the center of the head (M), and the shape and size of the head (M). Correction may be performed.

Signals indicating the distance l ₀ and the time differences t ₁ and t ₂ are sent to an angle calculation circuit (20).

The aural time difference detecting circuit (19), corresponding in pulse signal and the second pulse signal of the edge detection circuit (15) described above is shown in [Delta] T ₃ the first edge detection circuit (15) in FIG. 2 detecting the time difference t ₃ between the pulse. Signal indicating the time difference t ₃ is transmitted to the angle calculating circuit (20).

In the angle calculating circuit (20), the time differences t ₁ , t ₂ ,
An arrow θ ₀ is shown in FIG. 3 using t ₃ , the distance l ₀ , the sound velocity V, and the radius r of the head (M). The angle θ ₀ indicating the direction of the head (M) is calculated. The above angle θ
₀ can be determined by, for example, θ ₀ ≒ sin ^-1 ｛V ² (t ₁ + t ₂ ) t ₃ / 4rl｝ (1st formula). Then, using the position of the ultrasonic speaker (13) as a reference position of the virtual sound source, from the information of the angle θ ₀ and the distance l ₀ indicating the relative positional relationship between this reference position and the listener's head (M), The rotation angle θ position of the upper head of the head (M) with respect to the desired virtual sound source position and the relative distance 1 from the virtual sound source are calculated.

The angular position information of the listener obtained by the angle calculation circuit (20) is supplied to a control circuit (21).

In the acoustic signal reproducing device of this embodiment, the arithmetic unit (14) includes transfer characteristic information indicating transfer characteristics from a virtual sound source to the listener's both ears in only one quadrant of the rotational angle position of the listener's head; For example, as shown in FIG. 4, a storage circuit (22) for storing transfer characteristic information for each of the predetermined angles θ _{11 to} θ _1n in the first quadrant is provided.

Then, based on the current angle position information calculated by the angle calculation circuit (20), the control circuit (21) determines whether the current angle position exists in the first quadrant of FIG. The transfer characteristic information corresponding to the current angle θ _{11 to} θ _1n position is read from the storage circuit (22) as it is, and when the current angle position exists in the second quadrant of FIG. From (22), the current angles θ _{21 to} θ _2n are calculated using the first angle
The transfer characteristic information corresponding to the angles θ _{11 to} θ _{1n of the} quadrants is read out. If the current angular position is present in the third quadrant of FIG. 4, the transfer characteristic information is read from the storage circuit (22). The transfer characteristic information in which the angles θ _{31 to} θ _3n are associated with the positions of the angles θ _{11 to} θ _{1n in} the first quadrant is read out, and the current angular position is present in the fourth quadrant of FIG. In this case, the transfer characteristic information in which the current angles θ _{41 to} θ _4n correspond to the positions of the angles θ _{11 to} θ _{1n in} the first quadrant is read out from the storage circuit (22), and the transfer characteristic information is read. A signal indicating the quadrant to which the angular position belongs is supplied to the acoustic signal processing circuit (23).

Here, since the listener's head has a substantially spherical rotationally symmetrical shape, the transfer characteristics from the virtual sound source to the listener's both ears can be treated as symmetrical in each name.

The control circuit (21) reads two pieces of transfer characteristic information near the head rotation angle position indicated by the angle position information from the storage circuit (22), and performs, for example, a linear interpolation process or the like on the current head position. The transmission characteristic information at the part rotation angle position may be calculated.

The left and right channel sound signals S _L and S _R output from the sound signal supply source (22) are supplied to the sound signal processing circuit (23).

Note that the audio signal supply source (24) is a device that outputs predetermined left channel and right channel audio signals S _L and S _R , and includes, for example, various recording disk reproducing devices, recording tape reproducing devices, or It is a radio wave receiving device or the like.

The sound signal processing circuit (23) adds a predetermined transfer characteristic from the virtual sound source to both ears of the listener to the left and right channel sound signals S _L and S _R sent from the sound signal supply source (24). And a first to sixth changeover switches (25) for switching signal lines.
L), (25R), (26L), (26R), (27L), (27R), and first to fourth signal processing units (28a), (28b), and (28c) that perform processing for giving transfer characteristics. , (28d), etc.

The first to sixth changeover switches (25L), (25
R), (26L), (26R), (27L), and (27R) are controlled to be switched using a signal indicating the quadrant to which the current angular position belongs supplied from the control circuit (21) as a control signal. You.

The first changeover switch (25L) and a second changeover switch (25R) is an input switching of the left channel acoustic signal transmitted from the audio signal source (24) S _L and the right channel audio signal S _R performs, when the current angular position belonging to the first quadrant or the third quadrant, the right channel acoustic signal S _R to the first and second signal processing section (28a), supplied to (28b) then Moni, the left channel acoustic signal S _L said third and fourth signal processing section (28c), is supplied to (28d), also the current angular position belonging to the second quadrant or the fourth quadrant in the case, the left channel acoustic signal S _L to the first and second signal processing unit (28
a), (both supplied to 28b), the right channel acoustic signal S _R to the third and fourth signal processing section (28c), (28
d).

The third changeover switch (26L) and the fourth
Selector switch (26R) are acoustic signals E _L of the left and right channels outputted from the sound signal processing circuit (23), which performs output switching for E _R, the current angular position first quadrant or the third quadrant And when it belongs to the first
And the output signal of the first adder (29R) for adding the output signals of the third signal processing units (28a) and (28c) is selected as the sound signal E _R of the right channel, and the second and fourth signals are selected. signal processing unit (28b), is selected as the second adder acoustic signal the output signal of the left channel (29L) E _L for adding the output signal of (28d), also the current angular position the second quadrant or the case that belongs to the fourth quadrant, both to select the first adder the output signal (29R) as the acoustic signal E _L of the left channel, the second adder output signal (29L) Select as the sound signal E _R of the right channel.

Further, the fifth changeover switch (27L) and the sixth changeover switch (27R) provide left and right channel sound signals E _L and E _R output from the sound signal processing circuit (23).
And performs the filter switching, to the when the current angular position belonging to the first quadrant or the second quadrant, the acoustic signal of the left and right channels E _L, the E _R is output as it is, the current angular position is first When in the second or fourth quadrant,
The audio signals E _L and E _{R from} which high-frequency components have been removed by the low-pass filters (30L) and (30R) are output.

Each of the signal processing units (28a), (28b), (28c), (28
In d), based on the transfer characteristic information supplied from the control circuit (21), a pair of left-channel and right-channel loudspeaker devices, which are installed opposite to the listener and separated from each other, are used as a virtual sound source. An impulse response is set which represents the transfer characteristics of the listener to each ear when reproducing the channel and right channel audio signals S _L and S _R.

That is, the first signal processing unit (28a) generates an impulse response {h _RR (t, θ)} representing a transfer characteristic of the reproduced sound of the right channel audio signal S _R to the right ear.
Set. The second signal processing unit (28b) is an impulse response {h _RL (t, θ)} that represents a transfer characteristic of the reproduced sound of the right channel sound signal S _R to the left ear.
Set. It said third signal processing section (28c) is the impulse response of the left channel acoustic signal S _L to express transfer characteristics for the right ear of the sound reproduced _{{h LR (t, θ)} }
Set. The fourth signal processing section (28d) is the impulse response of the left channel acoustic signal S _L to express the transfer characteristic for the left ear of the sound reproduced _{{h LL (t, θ)} }
Set.

When the current angular position of the listener's head belongs to the first quadrant, the right channel acoustic signal S _R, the first signal processing section (28a) and the second signal processing unit ( 28
sent to b). In the first signal processing section (28a), subjected the impulse response _{{h RR (t, θ)} } a signal processing by convolutional integration of the above right channel acoustic signal S _R. Further, the second signal processing unit in (28b), the impulse response _{{h RL (t, θ)} } a signal processing by convolutional integration of applying to the right channel acoustic signal S _R.

Further, the left channel acoustic signal S _L is fed to the third signal processing section (28c) and the fourth signal processing section (28d). In the third signal processing section (28c), the impulse response _{{h LR (t, θ)} } convolving signal processing by the applied to the left channel acoustic signal S _L. Also,
In the second signal processing section (28d), the impulse response _{{h LL (t, θ)} } convolving signal processing by the applied to the left channel acoustic signal S _L.

Then, the output signals of the first signal processing unit (28a) and the third signal processing unit (28c) are supplied to the right adder (29R) and are added to each other. This right side adder (29R)
The output signal of is regenerated is sent to the right headphone unit (2R) as a right ear acoustic signal E _R via the right amplifier (31R). Further, the second signal processing section (28b)
The output signal of the fourth signal processing unit (28d) is supplied to the left adder (29L) and added to each other. The output signal of the left adder (29L) is regenerated is sent to the left headphone unit (2L) as the acoustic signal E _L for the right ear through the left amplifier (31L).

Also, when the current angular position of the listener's head belongs to the second quadrant, the input and output left and right channels are switched, and the same processing as in the first quadrant described above is performed, so that a sense of front localization is obtained. Obtainable. Further, when the current angular position of the listener's head belongs to the third and fourth quadrants, the same processing as in the first and second quadrants is performed, and the low-pass filters (30L), (30R) By outputting the acoustic signals E _L and E _{R from} which the high-frequency components have been removed, a feeling of backward localization can be obtained.

In the audio signal reproducing apparatus of the embodiment configured as described above, the listening position calculated by the angle calculation circuit (20) based on the transfer characteristic information of the first quadrant stored in the storage circuit (22). The above-mentioned sound processing is performed by forming transmission characteristic information at a rotation angle position corresponding to the movement of the listener's head and real-time responding to a change in the transmission characteristic due to the movement of the listener and the rotation of the head (M). By applying the left and right channel sound signals S _L and S _R by the signal processing circuit (23), for example, A, B and C in FIG. 5 show the relative positional relationship between the virtual sound source and the listener. In addition, the virtual sound source does not move similarly to the case where the sound signal is reproduced by the pair of speaker devices (SL) and (SR) installed in front of the listener (P) apart from each other so as to face the listener (P). Out-of-head localization, forward and rearward can get.

Here, in FIG. 5, the listener (P) approaches the virtual sound source from a state in which the listener (P) is positioned as indicated by A with respect to the pair of speaker devices (SL), (SR), that is, the virtual sound source. State B
C shows the state where the listener (P) has turned the head (M) to the right speaker device (SR) side. In the acoustic signal reproducing apparatus according to the present invention, the virtual sound source moves by performing the signal processing in real time in response to the change of the transfer characteristic accompanying the movement of the listener and the rotation of the head (M) as described above. A good sense of out-of-head localization and a sense of frontal localization can be obtained without performing, and binaural reproduction corresponding to any of the states A, B, and C in FIG. 5 can be performed.

H Effects of the Invention As described above, in the acoustic signal reproducing device according to the present invention,
Transfer characteristic information indicating a transfer characteristic from the virtual sound source to the listener's both ears in only one quadrant of the rotational angle position of the listener's head may be stored in the storage means. A small amount of transfer characteristic information to be stored and a small storage capacity can be used for the storage means.
Then, the acoustic signal processing means stores the transfer characteristic information at the head rotation angle indicated by the detection output by the detection means for detecting the rotation angle position corresponding to the movement of the listener's head in the storage means. It is formed based on the transfer characteristic information of only the quadrant, processes the left channel and right channel audio signals, respectively, and supplies the processed audio signals to the headphone device, so that even if the listener moves, the virtual sound source position is maintained. It is possible to perform proper binaural reproduction which can obtain a very natural sound image localization without moving.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing a configuration of an audio signal reproducing apparatus according to the present invention, FIG. 2 is a time chart schematically showing a state of a signal supplied to an arithmetic unit of the audio signal reproducing apparatus, FIG. 3 is a schematic diagram showing a distance and an angle calculated by the arithmetic unit of the audio signal reproducing device, and FIG. 4 is a diagram for explaining transfer characteristic information stored in a storage circuit of the arithmetic device of the audio signal reproducing device. FIG. 5 is a plan view showing the relative positional relationship between the virtual sound source and the listener for explaining the operation of binaural reproduction by the above-mentioned sound signal reproducing apparatus. (2L), (2R) ... Headphone unit (5L), (5R) ... Signal detector (10) ... Headphone device (11) ... Reference signal source (14) ... Computing device (20) ... Angle calculation circuit (21) Control circuit (22) Storage circuit (23) Sound signal processing circuit (24) Sound signal supply source

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Susumu Yabe 6-7-35 Kita Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (56) References JP-A-59-44197 (JP, A) 1-1121000 (JP, A) JP-A-1-112900 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04R 5/033

Claims (1)

(57) [Claims] 1. A detecting means for detecting a rotation angle position according to a movement of a listener's head, and a transmission from a virtual sound source to the listener's both ears in only one quadrant of the rotation angle position of the listener's head. Storage means for storing transfer characteristic information indicating characteristics; transfer characteristic information at a head rotation angle position indicated by a detection output by the detection means based on transfer characteristic information of only one quadrant stored in the storage means Sound signal processing means for processing sound signals of the left channel and the right channel, respectively, and reproducing the sound signal via the sound signal processing means by a headphone device. .