JPH0272798A - Acoustic signal regenerating device - Google Patents

Abstract

PURPOSE:To promptly, high-accurately, and stably detect the change of the direction of the head part of a listener by calculating the above-mentioned change based on the phase difference between the output signals of a pair of microphones to be arranged at two parts in the head part to pick up a detecting signal to be outputted from a detecting sound source. CONSTITUTION:For a headphone device 2, first and second microphones 3 and 4 are arranged for mutually separated two parts. A speaker 5 to be the detecting sound source is fixed and arranged to a position separated from the listener. An ultrasonic signal in a non-audible band is supplied from an ultrasonic signal source 7 to this speaker 5, and the speaker 5 outputs an ultrasonic wave to be the detecting signal. This ultrasonic wave is a so-called acoustic wave such as a bust wave for which the detection of its phase is made possible. The output signals of the microphones 3 and 4 are the signals obtained by picking up the acoustic wave to be outputted from the speaker 5, and an arithmetic unit 8 calculates the change of the direction of the head part based on the phase difference between the output signals of both the microphones and respectively processes the acoustic signals of a left channel and a right channel from an acoustic signal supplying source 16 based on transmission characteristics corresponding to the calculated direction of the above-mentioned head part.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an acoustic signal reproducing device that reproduces an acoustic signal using an electro-acoustic transducer unit that is worn on the head, such as a so-called headphone device. .

B0 Summary of the Invention The present invention is an acoustic signal reproducing device that reproduces an acoustic signal using a so-called headphone device or the like, in which a detection signal emitted from a detection sound source is placed at two locations on a listener's head. The change in the direction of the listener's head is calculated based on the phase difference between the output signals of these microphones, and the acoustic signal is processed using the transfer characteristic based on the calculation result. Due to its simple structure.

The direction of the listener's head can be detected stably, and a good sense of external localization and forward localization can be obtained.

C0 Prior Art Conventionally, as in a so-called headphone device, acoustic signals are reproduced using a pair of electro-acoustic transducer units that are mounted on the head of a listening shuttle and supported near the pinnae of both ears. In this case, a so-called pinaural system has been proposed as an acoustic signal reproducing apparatus that provides a good sense of direction of the sound image, a sense of localization outside the head, and the like.

The acoustic signal reproducing device that uses this pinaural method is
For example, as described in Japanese Patent Publication No. 53-283, predetermined signal processing is performed in advance on an acoustic signal reproduced by a headphone device. That is,
The sense of direction and localization of a sound image is determined by the volume difference, time difference, phase difference, etc. between the sounds heard by the left ear and the right ear. Therefore, the above-mentioned predetermined signal processing refers to the difference in distance between the sound source and the listener's left and right ears and the distance near the listener's head when sound is reproduced using a speaker device placed at a distance from the listener. This is signal processing that causes an acoustic effect equivalent to an acoustic effect caused by reflection, diffraction, etc. to occur in the sound reproduced by a headphone device. Such signal processing can be performed, for example, by supplying left ear and right ear audio signals to the headphone device via a level adjustment circuit, a delay circuit, etc., respectively.

By the way, when sound is reproduced using a speaker device placed at a distance from the listener, the absolute direction and position of the sound image do not change even if the listener rotates the direction of the head. The relative direction and position of the perceived sound image 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.

Due to the difference in the displacement state of the sound image with respect to changes in the direction of the listener's head, when playing back sound using a pinaural method using a headphone device, the sound field is formed inside the listener's head. Therefore, it is difficult to localize the sound image in the face of the listener, and the sound image in front tends to rise.

Therefore, conventionally, Japanese Patent Publication No. 42-227 and Japanese Patent Publication No. 5
As described in Japanese Patent Publication No. 4-19242, by detecting changes in the direction of the listener's head and changing the state of the signal processing based on the detection result, the headphone device can achieve a good forward direction. An acoustic signal reproducing device that provides a sense of localization has been proposed. In such an acoustic signal reproducing device, a direction detecting device such as a so-called gyroscope or a magnetic needle, and a movement detecting device such as a gear or a link device are disposed on the listener's head.

Then, based on the detection result from the direction detection device or movement detection device, the level adjustment circuit, delay circuit, etc. that process the audio signal are controlled, and the sound is reproduced by the speaker device placed at a distance from the listener. The aim is to obtain a sound field feeling similar to that of .

D. Problems to be Solved by the Invention By the way, the above-mentioned acoustic signal reproducing device uses a device that uses a gyroscope, a magnetic needle, gears, links, etc. as a device to detect the direction of the listener's head. We are prepared.

However, in a device using a gyroscope, the gyroscope itself is not only extremely expensive, but also large in size and weight, and further requires a large power source to operate. Therefore, this device is unsuitable as a device to be placed on the head of a freely moving listener and to detect changes in the direction of the head.

A device using a magnetic needle detects the direction of the listener's head based on the direction of the horizontal component of the earth's magnetism, and can be constructed at relatively low cost, small size, and light weight. It is something. However, since the responsiveness of direction detection is slow and stability is poor, changes in the direction of the listener's head cannot be detected quickly and with high precision.

Furthermore, a device using gears, link devices, etc. is a device that detects movement of the listener's head by rotation of gears, expansion and contraction of links, etc., with the listener's body as a reference. Not only does this inhibit the free movement of the patient's head, causing discomfort, but it also makes it impossible to perform highly accurate detection due to individual differences in the distance between the body and the head.

Therefore, an acoustic signal reproducing device equipped with these detection devices can quickly, accurately, and stably detect changes in the direction of the listener's head while having a device configuration that poses no practical problems. Therefore, it is difficult to obtain a good sound image localization feeling.

Therefore, the present invention is proposed in view of the above-mentioned circumstances, and has a simple configuration and can quickly change the direction of the listener's head when reproducing sound using a headphone device or the like. It is an object of the present invention to provide an acoustic signal reproducing device that can obtain a good sense of outside-of-the-head localization even in forward localization through highly accurate and stable detection.

E1 Means for Solving the Problems In order to solve the above-mentioned problems and achieve the above object, the acoustic signal reproducing apparatus according to the present invention includes a detection sound source for reproducing an acoustic signal in an inaudible band, and a detection sound source for reproducing an acoustic signal in an inaudible band A pair of microphones are arranged at two locations on the head and sense detection signals emitted from the detection sound source, and a change in the direction of the head is calculated based on a phase difference between the output signals of the pair of microphones. comprising a calculation means and an acoustic signal processing means for processing the left channel and right channel acoustic signals respectively based on the transfer characteristic corresponding to the direction of the head calculated by the calculation means, the acoustic signal processing means The acoustic signal transmitted through the listener is reproduced by a pair of electro-acoustic transducer units that are mounted on and supported by the listener's head.

F1 action In the acoustic signal reproducing device according to the present invention, a change in the direction of the listener's head causes a change in the direction of the listener's head to be detected by a pair of microphones disposed at two locations on the head that sense the detection signal emitted from the detection sound source. It is calculated by the calculation means based on the phase difference of the output signal, and the left channel and right channel acoustic signals are signal-processed according to the calculation result, so signal processing is always performed according to the direction of the listener's head. The applied acoustic signal is reproduced.

G. Examples Specific examples of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the acoustic signal reproducing device according to the present invention has a pair of left and right sides attached to the head M of a listener and supported near the listener's left and right auricles. There is a headphone device 2 comprising an electro-acoustic transducer unit (LL and IN). Above-pair electro-acoustic transducer unit) 1
t and 1 are units that convert the sent acoustic signal into sound and reproduce it. Further, in this headphone device 2, first and second microphones 3 and 4 are arranged at two locations spaced apart from each other, for example, on the left side and on the right side. These microphones 3 and 4 are configured to mainly sense sound in the inaudible band, for example, so-called ultrasonic waves.

A speaker 5 serving as a detection sound source is fixed and supported by, for example, legs 6 at a position spaced apart from the listener. This speaker 5 is an ultrasonic signal source 7
An ultrasonic signal, which is an acoustic signal in a more inaudible band, is supplied, and an ultrasonic wave serving as a detection signal is emitted. This ultrasonic wave may be, for example, a so-called burst wave in which a sound wave of a predetermined level is emitted intermittently at a predetermined time interval, as shown by A in FIG. This is a sound wave whose phase can be detected, such as a so-called level modulated wave that fluctuates.

The output signals of the first and second microphones 3.4 are:
This is a signal obtained by sensing the sound waves emitted from the speaker 5, and as shown by B and C in FIG.
A signal corresponding to the ultrasonic signal is output at a predetermined time interval after the ultrasonic wave is emitted. The output signals of these first and second microphones 3.4 are sent to a calculation device 8 serving as calculation means.

In the arithmetic device 8, the first microphone 3
The output signal of is sent to the first signal detection circuit 9, and the output signal of the second
The output signal of the microphone 4 is transmitted to the second signal detection circuit 10.
sent to. These first and second signal detection circuits 9.1
0 is a circuit that detects the rise of the output signals of the first and second microphones 3.4 and outputs them as pulse waves, as shown by D and E in FIG. The detection signals output from these first and second signal detection circuits 9.10 are as follows:
The signals are sent to the distance calculation circuit 11 and the binaural time difference detection circuit 12, respectively.

The ultrasonic signal is sent from the ultrasonic signal source 7 to the distance calculation circuit 11 via a third signal detection circuit 13 . This third signal detection circuit 13 is F in FIG.
As shown, the rising edge of the ultrasonic signal is detected and output as a pulse wave. This distance calculation circuit 11 is
The time difference between corresponding pulses in the output signal of the third signal detection circuit 13 and the output signal of the first signal detection circuit 9, indicated by ΔTl in FIG. 2, is 1. and ΔT2 in Figure 2.
A time difference t2 between corresponding pulses in the output signal of the third signal detection circuit 13 and the output signal of the second signal detection circuit 10 is detected. And each of these time differences 1. ,1. Based on the sound velocity V and the sound velocity V, the distance C between the speaker 5 and the center of the listener's head M, which is indicated by arrow 2 in FIG. 3, is calculated.

Note that the sound speed V may be set in advance as a constant in the distance calculation circuit 11, or may be changed in accordance with changes in temperature, humidity, atmospheric pressure, etc. Furthermore, when calculating the above distance, corrections are made based on the positional relationship between the first and second microphones 3.4 and the center of the head M, and the shape and size of the head M. It's okay.

Above distance! and each of the above time differences 1. ．． 1. No signal is shown,
It is sent to the angle calculation circuit 14.

The binaural time difference detection circuit 12 detects a time difference between corresponding pulses in the output signal of the first signal detection circuit 9 and the output signal of the second signal detection circuit 10, indicated by ΔT in FIG. Detect. The signal that also shows this time difference of 3 is
It is sent to the angle calculation circuit 14.

In the angle calculation circuit I4, each of the time differences u+,
Using Lz, T, y, the distance 2, the speed of sound V, and the radius r of the head M, 1 is indicated by the arrow θ in FIG.
An angle θ indicating the direction of the head M is calculated. This angle θ
For example, θ'r S in (V2(t+ +Lz)tz/4r
e)・・・・・・・・・(“Equation 1)” The signal indicating this angle θ is
The signal is supplied to a signal processing circuit 15 serving as an acoustic signal processing means.

The pair of electro-acoustic transducer units LL, i
l+, left channel and right channel acoustic signals SL output from the acoustic signal supply source 16;

S, l are further amplified and supplied via the signal processing circuit 15 by a pair of left and right amplifiers 17t, 17- corresponding to each of the electro-acoustic transducer units (IL, LM).

The audio signal supply 1ate is a device that outputs predetermined left channel and right channel audio signals St, S*, and is, for example, various recording disk playback devices, recording tape playback devices, or radio wave reception devices. .

The signal processing circuit 15 is a circuit that performs predetermined signal processing on the sent left channel and right channel acoustic signals SL, S, and calculates the angle θ from the angle calculation circuit 14.
The first to fourth signal processing units 1 are supplied with a signal indicating the
8a, 18b, 18C, and 18d. In each of these signal processing units 18a, 18b, 18c, and 18d, based on the angle θ, a pair of speaker devices for the left channel and right channel installed facing the listener are used for the left channel and the right channel. An impulse response is set that expresses the transfer characteristics to each ear of the listener when the right channel acoustic signals St, S* are reproduced.

That is, the first signal processing unit 18a generates an impulse response (hi, l(t,
θ)). The second signal processing section 18b is
An impulse response (hi
Set t(t, θ)). The third signal processing unit 18c sets an impulse response (hL*(1, θ)) expressing the transfer characteristic of the sound reproduced from the left channel sound signal S to the right ear. The fourth signal processing unit 18d sets an impulse response (htt(t, θ)) that expresses the transfer characteristics of the sound reproduced from the left channel sound signal SL to the left ear.

Note that each of these impulse responses may be set in advance in correspondence with the angle θ and stored in a memory device (ROM) or the like, and the subsequent address may be determined and read out based on the angle θ.

In this signal processing circuit 15, the right channel acoustic signal S is transmitted to the first and second signal processing sections 18a and 1.
Sent to 8b. The first signal processing section 18a performs convolution and integration processing using the impulse response (hB(L, θ)), and the second signal processing section 18b
In the above impulse response (h++Ilt,
Convolution and integration processing is performed using θ)).

Further, the left channel acoustic signal SL is sent to the third and fourth signal processing sections 18c and 18d. 3rd above
In the signal processing unit 1.8c, convolution and integration processing is performed using the impulse response (hLR(t, θ)), and in the fourth signal processing unit 18d, the impulse response (h-th signal) is processed.

(1, θ)).

and the first and third signal processing sections 18a.

The output signals of 18c are added together by a right-side adder 19□. The output signal of the right adder 19□ is sent to the right electro-acoustic transducer unit 18 via the right amplifier 17 as a right ear acoustic signal ER, and is reproduced.

Also, the second and fourth signal processing sections 18b.

The output signals of 18d are added together by a left side adder 19t. The output signal of the left adder 19L is sent to the left electro-acoustic transducer unit 114 as a left ear sound signal E via the left amplifier 17L and is reproduced.

In the acoustic signal reproducing device according to the present invention configured as described above, even if the angle θ indicating the direction of the listener's head M changes, this angle θ can be detected instantaneously. The left channel and right channel acoustic signals SL and SR are processed based on the angle θ. Therefore, it is possible to obtain a good sense of localization outside the head and a sense of forward localization similar to when reproducing acoustic signals using a pair of speakers and a single device placed in front of the listener and facing the listener. As the distance between the listener and the speaker device increases, the transmission characteristics of the sound reproduced by a pair of speaker devices installed in front of the listener at a distance from the listener change.
Changes due to changes in distance are reduced. Therefore, in the above-mentioned embodiment, the distance 2 is set to, for example, a short distance, a medium distance,
So-called presets that allow you to select from a long distance, etc.
A signal indicating the selected distance may be input to the angle calculation circuit 14 using a predetermined input device or the like.

Moreover, the above distance l is approximately as follows: 1"=V (t+ + tz)/2...
...It can be calculated by (2nd formula). When calculating the distance p using the second equation above, by substituting this second equation into the first equation above, θζSin″′(■t3/2r)...(Third equation) This means that the angle θ can be calculated.

In these cases, there is no need to use the distance calculation circuit 11 and the third signal detection circuit 13, and the output signals of the first and second signal detection circuits 9 and 10 are sent only to the binaural time difference detection circuit 12. The output signal of the ultrasonic signal source 7 is supplied only to the speaker 5. Even with this configuration, a change in the angle θ indicating the direction of the listener's head M is detected instantaneously, and each acoustic signal SLISR of the left channel and right channel is processed based on the detected angle θ. Therefore, it is possible to obtain a substantially good sense of external localization and a sense of forward localization.

Furthermore, in the above-described embodiment, the signal processing performed in the signal processing circuit 15 is not limited to the convolution integral processing using impulse responses, but also the amplitude-frequency characteristics of the sound transmitted to each ear of the listener. The signal processing may be performed by a signal level adjustment circuit and a signal delay circuit based on the transfer function that determines the phase frequency characteristic and the time difference in which the sound reaches each ear.

As shown in FIG. 4, the acoustic signal reproducing device according to the present invention maintains the speaker 5 serving as the detection sound source in a relatively fixed state even if the direction of the listener's head M changes. For example, the listener may be placed on the body of the listener.

That is, in this example, the headphone equipment W2 is
As shown in FIGS. 4 and 5, the pair of electro-acoustic transducer units IL, 1 and 1 have an acoustic signal for supplying a left ear acoustic signal EL and a right ear acoustic signal ER, respectively. The signal input cable 20 and the microphone output cable 21 for sending the output signals of the first and second microphones 3.4 to the arithmetic unit 8 are bundled into one cable with their covering members joined to each other. It is composed of

The speaker 5 is connected to each of the cables 20 and 21.
It is attached to the sheathing member in the middle of the bundled cable. Note that an ultrasonic signal supply cable 2 supplies ultrasonic signals from the ultrasonic signal source 7 to the speaker 5.
The sheathing of cable 20.2 is also joined to the sheathing of cable 20.21. The speaker 5 is attached so as to be supported on the listener's chest when the headbond device 2 is worn by the listener.

Further, the ultrasonic signal source 7, the arithmetic device 8, the signal processing circuit 15, the acoustic signal supply source 16, etc. are housed in the housing 2.
3 and is constructed as an integral part.

In the acoustic signal reproducing apparatus according to the present invention configured as described above, the position of the speaker 5 disposed on the chest of the listener is used as a reference, and the position of the head of the listener is adjusted as in the above embodiment. An angle θ indicating the direction of M is detected. and,
The left channel and right channel sound signals SL and SR are processed based on the detected angle θ, and a good sense of external localization and forward localization is obtained.

Note that the headphone device 2 constituting this acoustic signal reproducing device may be of a so-called auricular insertion type, as shown in FIG. Furthermore, the speaker 5 may be attached to the listener's back as shown in FIG. In these cases as well, it is possible to obtain a good sense of external localization and a good sense of forward localization, as in each of the above-described embodiments.

1-(, Effects of the Invention As described above, in the acoustic signal reproducing device according to the present invention, the direction change of the listener's head is determined by the detection signal emitted from the detection sound source, with the detection sound source as a reference. It is calculated by the calculation means based on the phase difference between the output signals of a pair of microphones arranged at two places on the head that sense the .

This device detects changes in the direction of the listener's head,
Changes in direction can be detected quickly, accurately, and stably, and the configuration is simple, making it easy to reduce size and weight.

Then, the audio signals of the left channel and the right channel are subjected to signal processing according to the calculation results.

Therefore, it is possible to always reproduce an acoustic signal that has been subjected to signal processing according to the direction of the listener's head.

That is, the present invention has a simple configuration when reproducing sound using a headphone device or the like, and quickly, accurately, and stably detects changes in the direction of the listener's head. It is possible to provide an acoustic signal reproducing device that can provide a good sense of outside-of-the-head localization with respect to forward localization.

[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 arithmetic unit of the audio signal reproducing device. FIG. 3 is a schematic diagram showing distances and angles calculated by the arithmetic unit of the acoustic signal reproducing device. FIG. 4 is a block diagram schematically showing another example of the configuration of the audio signal reproducing device, FIG. 5 is a perspective view showing the configuration of a headphone device constituting this audio signal reproducing device, and FIG. The figure is a perspective view showing another example of the configuration of the headphone device constituting this acoustic signal reproducing device, and FIG. 7 is a perspective view showing still another example of the configuration of the headphone device constituting this acoustic signal reproducing device. It is. M......Head of the listener

Claims (1)

[Claims] A detection sound source that reproduces an acoustic signal in an inaudible band, and a pair of microphones that are placed at two locations on the listener's head and that sense the detection signal emitted from the detection sound source. and a calculation means for calculating a change in the direction of the head based on the phase difference between the output signals of the pair of microphones, and a left channel based on the transfer characteristic corresponding to the direction of the head calculated by the calculation means. and an acoustic signal processing means for processing the acoustic signals of the right channel, respectively, and the acoustic signal transmitted through the acoustic signal processing means is transmitted to a pair of electro-acoustic transducers mounted and supported on the head of the listener. An acoustic signal reproducing device that is reproduced by a unit.