JPH03296400A - Audio signal reproducing device - Google Patents

Abstract

PURPOSE:To attain binaural reproduction with high degree of freedom by processing left and right channel audio signals respectively based on transmission characteristic information representing the transmission characteristic of a direct sound from a virtual sound source for each prescribed rotary angle in response to the movement of a head of a listener to both ears of the listener and supplying the processed sound to headphone device. CONSTITUTION:A couple of speakers 11 for left and right channels installed opposite to a listener P at an interval are used as virtual sound sources SL, SR, and impulse response of acoustic output from the virtual sound sources to both ears YL, YR of the listener is measured for each prescribed rotary angle in response to the movement of a head M of the listener P, and only the transmission characteristic information for the direct sound obtained by cancelling the characteristic of the speaker 11 used for the measurement and the characteristic of the sound field at the measurement is stored in advance in a memory 25 by using a head rotary angle theta as an address. The transmission characteristic information at the head rotary angle of the listener P represented by a detection output from signal detectors 5L, 5R mounted to a headphone band 1 and a rotary angle detection section 14 is read out of the memory 25 and an acoustic signal processing section 23 applies the signal processing for binaural reproduction to the left and right channel sound signals.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an audio signal reproducing device for reproducing an audio signal using a headphone device.

B. Summary of the Invention The present invention stores in a storage means transfer characteristic information indicating the transfer characteristics of direct sound from a virtual sound source to both ears of the listener at each predetermined rotation angle according to the movement of the listener's head. the rotation angle of the listener's head is detected by the detection means, and the acoustic signal processing means reads out the transfer characteristic information at the head rotation angle indicated by the detection output of the detection means from the storage means, This system processes the sound signals of the channel and the right channel, respectively, and can perform pinaural reproduction of any virtual sound source.

C. Conventional Technology Conventionally, as in a headphone device that reproduces an acoustic signal using a headphone unit, sound is transmitted by a pair of headphone units supported in correspondence near the pinnae of both ears by being worn on the listener's head. A pinaural system is known as a method for improving the sense of direction of a sound image, the sense of localization outside the head, etc. when reproducing a signal.

The sound reproduction system that uses this pinaural method is
For example, as described in Japanese Patent Publication No. 53-283, predetermined signal processing is performed on the acoustic signal reproduced by a headphone device.

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

The above-mentioned signal processing refers to, for example, when reproducing sound using a speaker device placed apart from the listener, the distance from the sound source, that is, the speaker device, to the listener's left and right ears is different, and the distance near the listener's head is adjusted. Headphones have an acoustic effect that equalizes the acoustic effect caused by reflection, diffraction, etc. signal processing to occur in the acoustic output reproduced by.

Such signal processing is performed, for example, by convolving and integrating an impulse response corresponding to the above-mentioned acoustic effect with the acoustic signals for the left ear and the right ear.

By the way, when sound is reproduced using a speaker device placed at a distance from the listener, the absolute position of the sound image does not change even if the listener moves or rotates the head direction. The relative direction and position of the sound image perceived by the user changes. On the other hand, when playing back sound using a pinaural method using a headphone device, when the listener rotates the direction of the head, the headphone device also rotates with the head, so the relative sound image perceived by the listener is The direction and position of the object do not change.

When performing pinaural playback using a headphone device in this way, a sound field is formed inside the listener's head due to differences in the displacement state of the sound image with respect to changes in the direction of the listener's head. It is difficult to localize the sound in front of the listener, and the sound image in front of the listener tends to rise.

Therefore, conventionally, Japanese Patent Application Laid-open No. 42-227 and Japanese Patent Publication No. 54
As described in Publication No. 19242, by detecting changes in the direction of the listener's head and changing the signal processing state based on the detection results, a headphone device can achieve a good sense of forward localization. An acoustic signal reproduction system has been proposed. In such an acoustic signal reproduction system, a direction detection device such as a so-called gyro compass or a magnetic needle is disposed on the listener's head.

Then, based on the detection result by the direction detection device, the level adjustment circuit, delay circuit, etc. that process the acoustic signal are controlled to produce a sound similar to that reproduced by the speaker device arranged at a distance from the listener. It is an attempt to gain ire.

In a conventional pinaural playback system in which a headphone device is equipped with a direction detection device such as the above-mentioned gyro compass,
By controlling the content of signal processing applied to the acoustic signal according to changes in the direction of the listener's head, it is possible to obtain a good sense of sound image localization.

In this way, in order to control the content of signal processing applied to acoustic signals in response to changes in the direction of the listener's head, transmission corresponding to the acoustic effects to be applied to the acoustic signals for the left ear and the right ear must be performed in advance. It is necessary to measure the characteristic information at every predetermined rotation angle according to the movement of the listener's head and store it in the storage means.

Conventionally, as shown in FIG. 6, the above-mentioned transfer characteristic information is based on the impulse response from a sound source <sp> in a certain sound field (LS) to the listener's (P) binaural ears (YL) and (VR).
By measuring at the position of the sound source (SP)
characteristic information h5P(t, θ), and direct sound transfer characteristic information hDL(t, θ), hDll from the sound source (SP) to both ears (1) and (YR) of the listener (P). (t,
θ) and the distance from the sound source (SP) to the listener's (P) ears (Y
L), including characteristic information h5L(t, θ) and hs*(t+θ) of the sound field (As) leading to (Yl?),
hL(t, θ)±hsp(t, θ) umbrella 11st(t;
θ) Umbrella h 5L(t, θ) h *(t, θ) −h 5
r(t, θ) umbrella 11+++(t, θ) rate h□(1,0)
Transfer characteristic information from the sound source (SP) to both ears (YL) and (YR) of the listener (P) expressed as +1t(t
, θ), ha(t.

θ).

D. Problem to be solved by the invention By the way, as mentioned above, from the sound source (SP) to the listener (P)
In addition to the direct sound transmission characteristic information fisL (t, θ) + h on (t, θ) reaching both ears (YL)' and (YR), the characteristics hsp (t, θ) of the sound source (SP) and From the above sound source (SP) to both ears (ML) of the listener (P), (Y
Characteristic information hs*(t, θ) of the sound field (AS) leading to R)
), h5R(t, θ), transfer characteristic information hL(t
, θ), hl(t, θ) in a storage means and performs pinaural reproduction. (
AS) characteristic information hst(t+θ), h□(1, θ) determines the characteristics of the virtual sound source and sound field to be reproduced pinaurally, making it impossible to perform pinaural reproduction with a high degree of freedom. . In addition, the above sound field (AS
) characteristic information h 5L (t, θ), h s* (t, θ)
contains reflection components and reverberant components, so it required long calculations to convolute and integrate the impulse responses corresponding to the acoustic effects with the acoustic signals for the left and right ears. .

SUMMARY OF THE INVENTION In view of the above-mentioned conventional circumstances, it is an object of the present invention to make it possible to shorten the calculation processing time for pinaural reproduction and to perform pinaural reproduction with a high degree of freedom. It is something.

EIII! Means for Solving the Problems In order to achieve the above-mentioned object, the acoustic signal reproducing device according to the present invention reproduces sound signals that reach both ears of the listener from a virtual sound source at each predetermined rotation angle corresponding to the movement of the listener's head. a storage means for storing transfer characteristic information indicating the transfer characteristic of the direct sound; a detecting means for detecting the rotation angle of the listener's head; and a detecting means for detecting the rotation angle of the listener's head; and acoustic signal processing means for reading out from the storage means and processing the left channel and right channel acoustic signals based on the transfer characteristic information, and reproducing the acoustic signals via the acoustic signal processing means with a headphone device. It is characterized by:

F Function In the acoustic signal reproducing device according to the present invention, the storage means includes:
The detection means stores transfer characteristic information indicating the transfer characteristics of direct sound from the virtual sound source to both ears of the listener at each predetermined rotation angle according to the movement of the listener's head. Detect the rotation angle of the part. And the acoustic signal processing means,
Transfer characteristic information at the head rotation angle indicated by the detection output of the detection means is read from the storage means, the left channel and right channel audio signals are processed, and the processed audio signals are supplied to the headphone device.

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

As shown in FIG.
The headphone device (10) is equipped with a headphone device (10) that is attached to the listener and supports a pair of headphone units (2L) and (2R) corresponding to the vicinity of the listener's left and right binaural valves. Two sliders (4L) and (4R) with protruding support arms (3L) and (3R) are slidably attached to the headband (1), and are composed of a reference signal source (11). A pair of signal detectors (SL) that sense reference signals for device detection.

(5R) is provided at the tip of the support arms (3L) and (3R). That is, the pair of signal detectors (5L) and (5R) are connected to the headband (1).
Slider (4L), (41
? ) protrudingly formed support arms (3L), (3R
), the headband (1) and the pair of headphone units (2L),
(2R) That is, it 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) includes an ultrasonic signal source (12) and an ultrasonic speaker (
13). An ultrasonic microphone is used for each of the pair of signal detectors (SL) and (SR) that sense the reference signal.

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

The pair of signal detectors (SL) and (SR) provided in the headphone device (10) sense a reference signal for position detection using ultrasonic waves sent from the ultrasonic speaker (13). The listener and the above ultrasonic speaker (1
3) and outputs each detection signal as shown in (B) and (C) of FIG.

The pair of signal detectors (SL) and (5R) are - a slider (slidably attached to the headband (1));
Support arms (3L) and (4R) protrude from each other.
L) and (3R) are provided at the tip of the headband (1) and a pair of headphone units (2L).
, (2R) That is, the headphone body is attached to the head (M) of the listener (P) and is supported by the support arms (3L) and (3R) at a position away from the headphone body in a light state, so that listening is possible. The person (P) moves or his/her head (
Even if M) is rotated, the head (P) of the listener (P)
The ultrasonic waves sent out from the ultrasonic speaker (13) can be extremely well sensed without being overshadowed by the noise, and the reference signal for position detection can be detected stably and accurately. In addition, the pair of signal detectors (5L) and (5R
) is the slider ( ) along the headband (1).
4L).

<4R) can be adjusted to the optimal position for detecting the reference signal for position detection by sliding the headband (1). The headphone unit (2L), (2) is worn and supported near both the left and right auricles of the listener (P).
The position of R) depends on the shape and size of the head (M) of the listener (P) and varies from person to person. Adjust the positions of the pair of signal detectors (SL) and (SR).

Each detection signal obtained by these signal detectors (5L) and (SR) is supplied to a rotation angle detection section (14).

The rotation angle detection section (14) includes first and second edge detection circuits (15) to which detection signals from the signal detectors (SL) and (5R) of the reference signal for position detection are supplied. , (16) and a third edge detection circuit (17) to which the 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), (1
6) detects each rising edge of each detection signal by each of the signal detectors (SL) and (5R), and detects the signals shown in (D) and (E) of FIG. 2 corresponding to the above rising edges. Output each pulse signal. 1st and 2nd above
Each pulse signal obtained by the edge detection circuits (15) 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 a rising edge as shown in FIG. 2 (F) corresponding to the rising edge. The third edge detection circuit (1) outputs a pulse signal such as
7) The pulse signal obtained by the above distance 1lI31E
It is supplied to the output circuit (18).

The distance calculation circuit (18) calculates the correspondence between the pulse signal obtained by the third edge detection circuit (17) and the pulse signal obtained by the first edge detection circuit (15) indicated by ΔT1 in FIG. The time difference tI between the pulses
and the time difference 1. between corresponding pulses in the pulse signal obtained by the third edge detection circuit (17) and the pulse signal obtained by the second edge detection circuit (16), indicated by ΔT2 in FIG. and detect. Based on these time differences 'l+'Li and the sound velocity V, the distance 1Ilj between the ultrasonic speaker (13) and the center of the listener's head (M), which is indicated by arrow 1 in FIG. !゛. Calculate.

Note that the sound speed V may be set as a constant in the distance calculation circuit (18) in advance, and may also be set as a constant in the distance calculation circuit (18).
The distance 11j may be changed in accordance with changes in atmospheric pressure, etc. . When calculating, corrections are made based on the positional relationship between each of the signal detectors (5L) and (5R) and the center of the head (M), and the shape and size of the head (M). It's okay.

Signals indicating the distance 10 and the time differences t)+tg are sent to the angle calculation circuit (20).

The binaural time difference detection circuit (19) has eight T3 in FIG.
A time difference t3 between corresponding pulses in the pulse signal of the first edge detection circuit (15) and the pulse signal of the second edge detection circuit (15) is detected. A signal indicating this time difference t is sent to the angle calculation circuit (20).

In the angle calculation circuit (20), each of the time differences tl+L
t, L5's above distance 10, above sound velocity ■ and above head (
arrow θ in FIG. 3 using radius r of M).

An angle θ0 indicating the direction of the head (M) is calculated. The above angle θ. For example, θ. ζ5in-'(V"(t++ tg)Lx/4
r no) ...... (Equation 1). The angle θ indicates the relative positional relationship between this reference position and the head (M) of the listener (P), with the position of the ultrasonic speaker (13) as the reference position of the virtual sound source (21). and distance 10, the above head (M) of the head (M) with respect to the desired virtual sound source position.
Calculate the rotation angle θ.

Listener (P) obtained by the above angle calculation circuit (20)
The rotation angle information of the head (M) of
).

The acoustic signal processing section (23) includes an acoustic signal supply source (2
4) are supplied with left channel and right channel audio signals S, , S, output from the terminal.

Note that the audio signal supply source (24) is a device that outputs predetermined left channel and right channel audio signals S, S, for example, various recording disk playback devices, recording tape playback devices, or, This is a radio wave receiving device, etc.

The acoustic signal processing section (23) includes the acoustic signal supply source (
It performs signal processing to give predetermined transfer characteristics from the virtual sound source to both ears of the listener to the left channel and right channel acoustic signals SL and SL sent from the memory (25) that stores the transfer characteristics. ) and this memory (
25) first to fourth signal processing circuits (26a) that perform signal processing to apply the transfer characteristics read from the left channel and right channel acoustic signals SL, S,
(26b), (26c), (26d), and these 10,000th to fourth signal processing circuits (26a), (26
b).

A right ear acoustic signal E and a right ear acoustic signal E are obtained from each acoustic signal subjected to signal processing according to (26c) and (26d).
first and second signal adders (27R) that combine L;
(27L).

Here, as shown in FIG. 4, the memory (25) stores a pair of speaker devices for a left channel and a right channel installed spaced apart from each other facing the listener (P) as a virtual sound source ( As SL) and (SR), each of the above listener's ears (YL) is output from these virtual sound sources (SL) and (SR).
) (YR) is measured at every predetermined rotation angle according to the movement of the head (M) of the listener (P), and the characteristics of the speaker device used for the measurement and the time of measurement are measured. Transfer characteristic information h□ (1, θ), tlmt (t, θ) of only the direct sound obtained by excluding the characteristics of the sound field.

hLm(t, θ) and htL(t, θ) are stored in advance using the head rotation angle θ as an address.

Then, the head rotation angle θ obtained by the rotation angle detection unit (14) is read out from the memory (25) and the transfer characteristic information hRm(t+θ)haL is read out from the memory (25).
(t, θ), hLm(t, θ), hLt(t, θ)
is read out.

Each transfer characteristic information h read from the memory (25)
□(1, θ), hi+t(t, θ), hLll(t, θ
), ThLt(t, θ) are the first to fourth signal processing circuits (26a) and (26b).

(26c) and (26d).

That is, the first signal processing circuit (26a) stores transfer characteristic information)1+u+(L, θ) indicating the impulse response of the direct sound to the right ear of the acoustic output that reproduces the right channel acoustic signal Sll. 25) and given. In addition, the second signal processing circuit (
26b) is provided with transfer characteristic information Th++L(t, θ) indicating the impulse response of the direct sound to the left ear of the acoustic output that reproduces the right channel acoustic signal S++, which is read out from the memory (25).

Furthermore, the third signal processing circuit (26c) contains transfer characteristic information h indicating the direct sound impulse response to the right ear of the acoustic output that reproduces the left channel acoustic signal SL.
Lm(t+θ) is read out from the memory (25) and given. Furthermore, the fourth signal processing circuit (
26d) is transfer characteristic information indicating the impulse response of the direct sound to the left ear of the acoustic output that reproduced the left channel acoustic signal SL.
) is read from and given.

In this acoustic signal processing section (23), the right channel acoustic signal Sll is sent to the first and second signal processing circuits (26a) and (26b).

The first signal processing circuit (26a) performs signal processing on the right channel acoustic signal St by convolution to give an impulse response represented by 1l(t, θ) based on the transfer characteristic information. In the second signal processing circuit (26b), the transfer characteristic information hmL(t, θ
) is applied to the above right channel acoustic signal S+t.
give to

Further, the left channel acoustic signal SL is sent to the third and fourth signal processing circuits (26c) and (26d).

The third signal processing circuit (26c) performs signal processing on the left channel acoustic signal SL by convolution to give an impulse response indicated by the transfer characteristic information hL*(t+θ). Further, in the fourth signal processing circuit (26d), the transfer characteristic information htt(t+θ)
The left channel acoustic signal SL is subjected to signal processing using convolution integration to give an impulse response represented by .

The first and third signal processing circuits (26a) (
The output signals of 26c) are supplied to the right side adder (27R) and added together. The output signal of the right-side adder (27R) is sent to the right-side headphone unit (2R) and reproduced as a right-ear acoustic signal E via the right-side amplifier (28R). Further, the output signals of the second and fourth signal processing circuits (26b) and (26d) are supplied to the left side adder (27[,) and added together.

The output signal of the left side adder (27L) is sent to the left side headphone unit (21,) as the right ear acoustic signal EL via the left side amplifier (28L) and reproduced, and is configured as described above. In the acoustic signal reproducing device of the embodiment, the current angular position information calculated by the angle detecting section (20) is used as a read address and the memory (20) is read.
Each transfer characteristic information is obtained from 5).

(1, θ), hmL (L, θ), h□ (1, θ), h
tt(t, θ) is read out, and based on this transfer characteristic information, signal processing is performed on the acoustic signal to correspond in real time to changes in the transfer characteristic accompanying movement of the listener (P) and rotation of the head (A). For example, as shown in FIG. 5 (A), (B), and (C), the relative positional relationship between the virtual sound source and the listener (P) is performed by the processing unit (23). ) A pair of speaker devices (SL) and (SR) placed in front of each other and separated from each other to face each other provide a good sense of localization outside the head and a virtual sound source that does not move, similar to when reproducing acoustic signals. Provides a sense of forward localization.

Here, in FIG. 4, the listener (P) speaks (
(B) shows the state in which the listener (P) approaches the virtual sound source from the state shown in A), and furthermore, the state in which the listener (P) rotates his/her head (M) toward the right speaker device (SR> side). is shown in (C).As described above, the acoustic signal reproducing device of this embodiment performs signal processing that corresponds in real time to changes in transfer characteristics accompanying movement of the listener and rotation of the head (M). By doing this, it is possible to obtain a good sense of localization outside the head and a sense of forward localization without moving the virtual sound source, and as shown in (A) in Fig. 5 above.
, CB), and (C) can be performed. Moreover, the above memory (2
5) contains information on the transfer characteristics of only the direct sound reaching each of the listener's ears (YL) and (YR) from the virtual sound sources (SL) and (SR), 1ll(t, θ).

b++t(Lθ), ht*(t,θ)+h tL(t
, θ), excluding the characteristics of the speaker device used to measure the transfer characteristics and the characteristics of the sound field at the time of measurement. time can be shortened.

In addition, it is possible to perform pinaural reproduction without being affected by the characteristics of the speaker device used to measure the transfer characteristics and the characteristics of the sound field at the time of measurement, and the desired speaker characteristic information and sound field characteristic information can be transferred to the first to fourth signal processing circuits (26a), (26b), (26c).

(26d), it is possible to perform pinaural reproduction in an arbitrary sound field using a virtual sound source having arbitrary speaker characteristics.

H Effects of the Invention As described above, the acoustic signal reproducing device according to the present invention can improve the transmission characteristics of direct sound from the virtual sound source to both ears of the listener at each predetermined rotation angle according to the movement of the listener's head. The transfer characteristic information at the rotation angle of the listener's head indicated by the detection output by the detection means is read out from the storage means, and the sound processing means is used to calculate the transfer characteristic information of the left channel and the right channel. Since the acoustic signal is subjected to signal processing for pinaural reproduction, it is possible to perform pinaural reproduction without being affected by the characteristics of the sound source or the characteristics of the sound field.Moreover, by using the transfer characteristic information of only direct sound, the above-mentioned The calculation processing time required for signal processing for pinaural reproduction can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram schematically showing the configuration of an audio signal reproducing device according to the present invention, and FIG. 2 is a time chart schematically showing the state of the signal supplied to the rotation angle detection section of the audio signal reproducing device. , FIG. 3 is a schematic diagram showing the distance and angle calculated by the rotation angle detection section of the acoustic signal reproducing device,
FIG. 4 is a plan view showing the relative positional relationship between a virtual sound source and a listener for explaining the transfer characteristic information stored in the memory of the audio signal reproducing device, and FIG. 5 is a plan view of the pinaural reproduction by the audio signal reproducing device. FIG. 3 is a plan view showing the relative positional relationship between a virtual sound source and a listener for explaining the operation. FIG. 6 is a plan view showing the relative positional relationship between a virtual sound source and a listener for explaining transfer characteristic information stored in a memory in a conventional audio signal reproducing device. (2L), (2R)...Headphone unit (5L), (5R)...Signal detector (1
0)・・・・・・・・・・・・ (11)・・・・・・・・・・・・ (14)・・・・・・・・・・・・ (23)・・・・・・・・・・・・ (24)・・・・・・・・・・・・ (25)・・・・・・・・・・・・ (26a) ~(26d) ・・・・・・(27L), (27R )...Headphone device reference signal source Rotation angle detection section Acoustic signal processing section Acoustic signal supply source Memory signal processing circuit Signal adder Patent Applicant: Sony Corporation

Claims (1)

[Scope of Claims] Storage means storing transfer characteristic information indicating the transfer characteristic of direct sound from a virtual sound source to both ears of the listener at each predetermined rotation angle according to the movement of the listener's head; a detection means for detecting the rotation angle of the head of the user; and transfer characteristic information at the head rotation angle indicated by the detection output of the detection means is read from the storage means, and based on this transfer characteristic information, the left channel and the right channel are detected. What is claimed is: 1. An acoustic signal reproducing device comprising: acoustic signal processing means for processing respective acoustic signals, and reproducing the acoustic signals passed through the acoustic signal processing means using a headphone device.