JP3500746B2 - Sound image localization device and filter setting method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound image localization device for realizing a virtual sound image in an AV (audio / visual) device and a method for setting a filter used therein.

[0002]

2. Description of the Related Art In recent years, it has been desired to develop a device that realizes virtual reality in the fields of video / audio / game. In the field of acoustics, techniques such as sound field control and sound image control have been particularly advanced, and development of devices that actually realize these techniques has been actively performed.

FIG. 1 is a block diagram of a conventional sound image localization apparatus, which will be described below with reference to the drawings.

First, a control speaker placed in front of the listener.
A method of localizing a sound image to the left rear of the listener using the power 6-1 and 6-2 will be described with reference to FIG. In FIG.
1 is an input signal S (t), 2 is an A / D converter, 3-1 and 3-2 are signal processing means (hereinafter referred to as a filter unit), 4-1 and 4-2 are D / D.
A converters, 5-1 and 5-2 are amplifiers, and 6-1 and 6-2 are control speakers.

FIG. 27 is a block diagram of the filter units 3-1 and 3-2. 12 is a calculation means for convolving the input signal and the tap coefficient, 14 is a controller for taking out a necessary coefficient from the coefficient memory 15 storing tap coefficients for convolution by the calculation means 12 according to the signal from the positional relationship input means 13, and 13 is a receiver It is a positional relationship input means for inputting a positional relationship between the listener and the virtual speaker.

A conventional sound image localization apparatus will be described below with reference to FIGS. 1 and 27. In FIG. 1, h1 (t) is the response at the position of the control speaker 6-1 and the left ear of the listener 8 (correctly, at the position of the eardrum when an impulse is input to the control speaker 6-1. , When the measurement is performed at the position of the auditory meatus entrance, the same applies to the following), the head related transfer function (hereinafter referred to as the impulse response for the purpose of explaining in the time domain. However, the same result can be obtained even when considered in the frequency domain. Obtained), h2 (t) is
The impulse response at the position of the control speaker 6-1, and the right ear of the listener 8, h3 (t), is the impulse response at the position of the control speaker 6-2 and the left ear of the listener 8, h4 (t). Is an impulse response at the position of the control speaker 6-2 and the right ear of the listener 8, 1 is a signal source for generating a signal S (t) such as an impulse signal, and 7 is arranged at the left rear of the listener. Virtual speaker,
h5 (t) is an impulse response at the position of the virtual speaker 7 and the listener 8's left ear, and h6 (t) is an impulse response at the position of the virtual speaker 7 and the listener 8's right ear. In addition, in FIG. 1 and FIG. 27, those having the same function are denoted by the same reference numerals.

In such a structure, when the signal S (t) is radiated from the virtual speaker 7 from the signal source 1, the listener 8
The sound that reaches the ear of the left ear L (t) is

[0008]

[Equation 1]

In the right ear R (t),

[0010]

[Equation 2]

(However, * represents a convolution operation.) (Actually, the transfer function of the speaker itself is multiplied, but this is ignored. The transfer function of the control speaker is h5 (t), h6
(It may be considered included in (t)).

Further, the impulse response and the signal S (t) are
Think of it as a digital signal with discrete time, and calculate L (t) → L (n) R (t) → R (n) h5 (t) → h5 (n) h6 (t) → h6 (n) S ( t) → S (n) (n is actually nT, T is a sampling time, but is generally expressed by omitting T. In addition, n is a natural number.) Equation 2) is as follows.

[0013]

[Equation 3]

[0014]

[Equation 4]

Here, N is the impulse response h5 (n), h
It is 6 (n) long. Similarly, the signal S (t) is the speaker
The sound radiated from 6-1 and 6-2 and reaching the listener 8 is, in the left ear L '(t),

[0016]

[Equation 5]

In the right ear R '(t),

[0018]

[Equation 6]

## EQU3 ## Similarly,

[0020]

[Equation 7]

[0021]

[Equation 8]

It becomes Assuming that sound can be heard from the same direction if the head-related transfer functions are equal (this assumption is generally correct),

[0023]

[Equation 9]

At the time,

[0025]

[Equation 10]

[0026]

[Equation 11]

At the time,

[0028]

[Equation 12]

Therefore, in order to allow the listener 8 to hear from the left rear which is the position of the virtual speaker 7 using the speaker 6-1 and the speaker 6-2, (Equation 10)) and ( It suffices to determine hL (n) and hR (n) so that Expression 12) is satisfied. For example, if (Equation 10) and (Equation 12) are rewritten in the frequency domain representation, the convolution operation is replaced with multiplication, and after that, each impulse response is FFT'ed into a transfer function. Since the transfer functions of the FIR filter other than the two are obtained by measurement, the transfer function of the FIR filter can be obtained from these two expressions. Using hL (n) and hR (n) thus determined, the signals S (n) and hL (n) from the control speaker 6-1 and the signal S (h) from the control speaker 6-2 are used.
By radiating a convolution of (n) and hR (n), the listener 8 can feel that a sound is coming from behind without actually sounding the virtual speaker 7 behind. Is possible.

FIG. 27 shows the filter units 3-1 and 3-shown in FIG.
2 is an internal block diagram of 2. FIG. A coefficient corresponding to the position input by the positional relationship input means 13 is set in the controller 14 from the coefficient memory 15, and the convolution processing is performed by the input signal and the convolution operation means 12 with this coefficient.

When a plurality of virtual sound sources are localized at the same time, as shown in FIG. 28, the calculating means 12-1a, 1 in the filter unit 3 are arranged.
It can be realized by connecting 2-2a in parallel.

By performing the above signal processing, it is possible to localize the sound image at an arbitrary position.

[0033]

However, in the above configuration, in order to realize an actual head-related transfer function from a low frequency range to a high frequency range, a large number of FIR filter taps are required. . As the number of taps increases, the load on the hardware increases, which hinders realization.
Therefore, generally, a method of reducing the number of taps and realizing sound image localization is used. However, a certain number of taps is necessary to maintain the accuracy of realization of the head-related transfer function, but reducing the number of taps may lead to blurring of the sound image and deterioration of bass. Also, a large amount of memory was required to store the coefficients of all angles used by the hardware.

The present invention has been made in view of the above problems of the prior art.
An object of the present invention is to provide a sound image localization device that can realize a localization feeling and sound quality comparable to the case of using only an arithmetic unit with a large number of taps, with a low-order IIR filter unit and an arithmetic unit with a small number of taps. Is. Also, in a sound image localization device that realizes multiple sound image localizations at the same time, a low-order IIR filter means and a calculation means with a small number of taps, with the same level of localization and sound quality as in the case of using only a conventional arithmetic unit with a large number of taps. It is an object of the present invention to provide a sound image localization apparatus that is realized by the above-mentioned IIR filter means and can reduce the hardware scale by combining them into one, and a filter setting method for combining the IIR filters.

[0035]

[Means for Solving the Problems]Sound image localization device
In order to solve the above problems,Position of listener and virtual image
Positional relationship input means for inputting positional relationship and digital audio
Position information from the positional relationship input means upon receiving a signal
A control signal for localizing the virtual sound image is output based on
And the output signal from the filter unit
A D / A converter for converting into an analog signal, and the D / A converter
The amplifier that amplifies the output of the converter
Equipped with a control speaker that emits a controlled signal to a predetermined area.
In the above sound image localization apparatus, the filter unit is a virtual sound image.
Location information of the first frequency domain
The first processing is performed by filtering according to the frequency characteristic (a) of
IIR filter means for outputting a logical signal, and the first processing
A signal, receiving the first processed signal and the first frequency
Predetermined for a second frequency region that is high in the wave number region
The convolution processing with the transfer function having the frequency characteristic (b) of
And a calculation means for outputting a second processed signal.
The predetermined frequency characteristic (a) and the predetermined frequency
The characteristic (b) is determined based on the position information of the virtual sound image.
The filter unit, the D / A converter, the amplifier,
And at least two sets of the control speakers
Is characterized by.

Secondly, the present invention provides IIR filter means for filtering the digital acoustic signal with a predetermined frequency characteristic to output a control signal, the control signal, a sound image localization filter and a convolution. The calculation means for processing is connected in parallel.

Thirdly, the present invention provides IIR filter means for filtering the digital acoustic signal with a predetermined frequency characteristic to output a control signal, the control signal, a sound image localization filter and a convolution. The configuration is such that a plurality of filters are connected in series with an arithmetic means that performs processing.

Fourthly, the present invention has a constitution in which a plurality of IIR filter means having substantially the same transfer characteristic in the frequency region of a predetermined frequency f0 or less of the filter unit of the third constitution is integrated. It is a thing.

Fifthly, in the present invention, in the filter section of the fourth structure, the virtual sound image of the first angle and the angle adjacent to the virtual sound image of the first angle are equal to or less than a predetermined frequency f0. A method of combining a plurality of IIR filter means having substantially the same transfer characteristics in the frequency domain is adopted.

Sixthly, according to the present invention, in the filter unit having the above-mentioned fourth construction, all virtual sound images in the range of the second angle are set to have an arbitrary angle within the range of the second angle. The method is to combine a plurality of IIR filter means having transfer characteristics that are substantially equal to the transfer characteristics that realize the virtual sound image of.

Seventhly, according to the present invention, a plurality of IIRs having the above-mentioned third structure are combined into a single filter unit, and a plurality of IIRs having substantially the same transfer characteristics in a frequency region of a predetermined frequency f0 or lower. This is a configuration in which the filter means is integrated.

Eighth, the present invention, in the above-mentioned fourth configuration, is adjacent to the virtual sound image at the first angle, the second angle symmetrical to the median plane of the listener, and the second angle. In all virtual sound images, a method is used in which a plurality of IIR filter means having substantially the same transfer characteristics in the frequency region below a predetermined frequency f0 are put together.

[0043]

In the sound image control apparatus of the present invention, the frequency characteristic of the IIR filter means and the frequency characteristic of the transfer function set in the computing means are determined when the transfer characteristic is determined based on the acoustic transfer characteristic from the virtual sound image to the listener. The low frequency region of IIR
It is realized (reproduced) by the filter means, and the high frequency region is realized by the calculation means. As described above, by combining the IIR filter means and the arithmetic unit, the acoustic transfer characteristic for realizing the virtual sound image is accurately realized by using the arithmetic unit having a shorter tap length than the conventional method.

Further, in the sound image control device of the present invention, by combining a plurality of IIR filter means having the same frequency characteristic into one, a sound image localization device similar to the conventional one can be realized with smaller scale hardware.

[0045]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) A sound image localization apparatus according to a first embodiment of the present invention will be described below with reference to the drawings. The same functions and functions as those of the conventional example are indicated by the same numbers and symbols.

FIG. 1 is an overall block diagram of a sound image localization apparatus in one embodiment of the present invention, and FIG. 2 is a block diagram of a portion related to a filter section of the present invention.

In FIG. 1, an input signal S (t) is input to the device, converted into a digital signal by an A / D converter 2, and then input to filter units 3-1 and 3-2 which are signal processing means. To be done. When the input signal is digital, the input signal S (t) may be directly input to the filter units 3-1 and 3-2.

On the other hand, the positional relationship input means 13 inputs the positional information of the virtual sound image 7 seen by the listener to the controller 14. As the position information, parameters indicating the angle, distance and height of the sound source viewed from the listener are input. Positional input means
According to the position input from 13, the controller 14 sets the filter coefficient from the coefficient memory 15 to the IIR filter means 11 and the arithmetic means 12. Example of configuration of IIR filter 11 Figure 3
Shown in. In FIG. 3, the two-stage configuration of the bike quad II
R filter is used. Reference numerals 31, 32, 33 and 34 are delay devices, 35, 36, 37, 38 and 39 are multipliers, and 40 is an adder. In this case, the calculation amount of the IIR filter means 11 is equal to the calculation amount of ten plus taps of the FIR filter.

The frequency characteristics (transfer function) of the IIR filter means 11 are the filter parts 3-1 and 3- for realizing the virtual sound image 7.
The transfer characteristic C of 2 (hereinafter referred to as a target characteristic) is set to match at a frequency equal to or lower than a predetermined frequency f0. The predetermined frequency f0 is preferably the lowest resonance frequency of the control speakers 6-1 and 6-2. FIG. 4 shows an example of the target characteristic in this embodiment, and FIG. 5 shows an example of the frequency characteristic of the IIR filter means 11 with respect to this target characteristic.
As can be seen from FIGS. 4 and 5, the frequency characteristic of the IIR filter means 11 substantially matches the target characteristic in the range of f0 or less. As a result, the bass range that could not be controlled without using a large number of taps in the conventional method is
By using the R filter means 11, it is possible to easily and faithfully reproduce.

The signal filtered by the IIR filter means 11 is input to the computing means 12. Computing means
12 can be configured by a FIR filter. FIG. 6 shows an example of the FIR filter forming the calculating means 12. 6
1, 62, 63, 64 are delay devices, 65, 66, 67, 6
8 is a multiplier and 69 is an adder. FIG. 7 shows the calculation means 12
Shows the frequency characteristic Cf of. Comparing with the target characteristic C shown in FIG. 4, it can be seen that Cf reproduces the same frequency characteristic as C in the region of the predetermined frequency f0 or higher.

FIG. 8 shows the impulse response of the target characteristic, and FIG. 9 shows an example of the impulse response realized by the calculating means 12 in this embodiment. From FIG. 8 and FIG. 9, in the conventional method, the frequency characteristic required for the calculating means 12 is 128 taps.
Although it was necessary to some extent, it can be seen that this embodiment can be realized with 32 taps. This effect is obtained because the characteristics on the low frequency side are realized by the IIR filter means 11.

FIG. 10 shows the filter units 3-1 and 3-2 of this embodiment.
Shows the frequency characteristics of. Comparing FIG. 10 with FIG. 4 showing the frequency response of the target characteristic, in the entire frequency band,
It can be confirmed that FIGS. 4 and 10 exactly match.
In other words, by combining the IIR filter means 11 and the calculating means 12 to form a hybrid structure, the frequency characteristic similar to the conventional method can be realized with the calculating means having a smaller number of taps than the conventional method.

The output signals from the filter sections 3-1 and 3-2 are input to the D / A converters 4-1 and 4-2, and the output signals of the D / A converter are input to the amplifiers 5-1 and 5-. Enter in 2. By radiating the outputs of the amplifiers 5-1 and 5-2 to a predetermined area using the control speaker, it is possible to realize sound image localization with the virtual sound image as the virtual speaker 7.

As described above, the frequency characteristic of the IIR filter means 11 is set as described above, and the IIR filter means 11 and the calculating means 12 are connected in series to form a hybrid structure, whereby the number of taps of the calculating means is reduced. Even if you drastically reduce
It is possible to accurately realize the transfer characteristic that realizes sound image localization. Therefore, an accurate control signal can be generated, and the same sound image localization effect as that of the conventional calculation means can be obtained. As described above, according to the present embodiment, it is possible to realize the localization feeling and the sound quality to the same degree as in the case of using only the conventional arithmetic unit with a large number of taps by the low-order IIR filter unit and the arithmetic unit with a small number of taps.

In this embodiment, the filter section, D / A
Two converters, two amplifiers, and two control speakers are used, that is, two sets are used. However, the present invention is not limited to this, and when three or more sets are used, the effect of two or more sets is obtained. Is possible. Further, in the present embodiment, the IIR filter means 11 has a biquad two-stage configuration, but the present invention is not limited to this, and the same effect can be obtained by changing the configuration to three stages or the like according to desired characteristics.

(Embodiment 2) A sound image localization apparatus according to a second embodiment of the present invention will be described below with reference to the drawings. The same numbers and symbols are used for the same functions as those in the conventional example and (Example 1).

FIG. 1 is an overall block diagram of a sound image localization apparatus in this embodiment, and FIG. 11 is a block diagram of a filter section according to the present invention.

In FIG. 1, the process is the same as (Example 1) until the input signal S (t) is input to the filter units 3-1 and 3-2.

The filter units 3-1 and 3-2 in FIG.
As shown in, IIR filter means 11, calculation means 12,
It is composed of an adder 16 that adds the output of the IIR filter means 11 and the output of the calculation means 12, and the IIR filter means 11 and the calculation means 12 are connected in parallel.

On the other hand, the positional relationship input means 13 inputs the positional information of the virtual sound image 7 viewed from the listener to the controller 14. As the position information, parameters indicating the angle, distance and height of the sound source viewed from the listener are input. Positional input means
According to the position input from 13, the controller 14 controls the IIR filter means 11 and the convolution processing means from the coefficient memory 15.
Set the filter coefficient to 12. The IIR filter means 11 can be realized by the configuration of FIG. 3 as in the case of the first embodiment. In this embodiment, a biquad IIR filter having a two-stage configuration is used. 31, 32, 33, 34 are delay devices, 3
5, 36, 37, 38, 39 are multipliers, and 40 is an adder. In this case, the calculation amount of the IIR filter means 11 is FIR
This is equivalent to the amount of calculation for dozens of taps of the filter. The calculating means 12 can be composed of a FIR filter. FIG. 6 shows an example of the FIR filter that constitutes the calculation means 12.
61, 62, 63, 64 are delay devices, 65, 66, 67,
68 is a multiplier and 69 is an adder. IIR filter means
The outputs of 11 and the arithmetic means 12 are added by the adder 16 to obtain the outputs of the filter units 3-1 and 3-2.

The sum of the frequency characteristic (transfer function) of the IIR filter means 11 and the frequency characteristic of the arithmetic means 12 is the transfer characteristic C of the filter units 3-1 and 3-2 for realizing the virtual sound image 7 (hereinafter,
It is set to match the target characteristic). However, if the frequency region below the predetermined frequency f0 is realized by using the calculating means, a very large number of taps are required. Therefore, in the present embodiment, the frequency region below the predetermined frequency f0 is set.
It is set so that it is mainly realized by the IIR filter means 11 and the frequency region above a predetermined frequency f0 is mainly realized by the calculation means 12. This predetermined frequency f0 is controlled by the control speakers 6-1, 6
A minimum resonance frequency of -2 is desirable.

FIG. 4 shows an example of the target characteristic in this embodiment, FIG. 12 shows an example of the frequency characteristic of the IIR filter means 11 for this target characteristic, and FIG. 13 shows the frequency characteristic of the calculating means 12 for this target characteristic. An example of the characteristic is shown in FIG. 14 as the sum of the frequency characteristic of the IIR filter means 11 and the frequency characteristic of the calculation means 12. By comparing FIG. 4 and FIG. 14, it can be confirmed that FIG. 4 and FIG. 14 exactly match in the entire frequency band.

FIG. 8 shows an example of the impulse response of the target characteristic, and FIG. 9 shows an example of the impulse response necessary for the calculating means 12 in this embodiment. From FIG. 8 and FIG. 9, in the conventional method, the frequency characteristic required for the calculating means 12 is 128 taps.
Although it was necessary to some extent, it can be seen that this embodiment can be realized with 32 taps. This is because the characteristics on the low frequency side are mainly IIR
This is because it is realized by the filter means 11. As a result, in the present embodiment, the low range that could not be controlled without using a large number of taps, in the present embodiment, IIR filter means
By using 11, it is possible to easily and faithfully reproduce with a small number of taps. In other words, by combining the IIR filter means 11 and the calculating means 12 and taking a parallel configuration, the calculating means with a smaller number of taps than the conventional method,
It is possible to realize the same frequency characteristics as the conventional method.

Output signals from the filter units 3-1 and 3-2 are D /
It is input to the A converters 4-1 and 4-2, and the output signal of the D / A converter is input to the amplifiers 5-1 and 5-2. By radiating the outputs of the amplifiers 5-1 and 5-2 to a predetermined area using the control speaker, it is possible to realize sound image localization with the virtual sound image as the virtual speaker 7.

As described above, the frequency characteristics of the IIR filter means 11 are set as described above, the IIR filter means 11 and the arithmetic means 12 are connected in parallel, and the outputs of the IIR filter means 11 and the arithmetic means 12 are added. With such a configuration, even if the number of taps of the calculating means is significantly reduced, the transfer characteristic for realizing sound image localization can be accurately realized. Therefore, an accurate control signal can be generated, and the same sound image localization effect as that of the conventional calculation means can be obtained. As described above, according to the present embodiment, it is possible to realize the localization feeling and the sound quality to the same degree as in the case of using only the conventional arithmetic unit with a large number of taps by the low-order IIR filter unit and the arithmetic unit with a small number of taps.

In this embodiment, the filter section, D / A
Two converters, two amplifiers and two control speakers are used, that is, two sets are used. However, the present invention is not limited to this, and when three or more sets are used, the effect of two or more sets is obtained. It is possible.

(Embodiment 3) A sound image localization apparatus for simultaneously localizing a plurality of virtual sound images according to a third embodiment of the present invention will be described with reference to the drawings.

The same numbers and symbols are used for the same functions as those of the conventional example and (Example 1) (Example 2).

FIG. 15 is an overall block diagram of a sound image localization apparatus according to an embodiment of the present invention for simultaneously locating two virtual sound images at adjacent positions on a concentric circle when viewed from the listener. It is a block diagram which concerns on the filter part of a present Example.

In FIG. 15, the input signal S (t) is A /
After being converted into a digital signal by the D converter 2, it is input to the filter units 3-1 and 3-2 which are signal processing means. When the input signal is digital, the input signal S (t) is directly input to the filter units 3-1 and 3-2.

On the other hand, the positions of the virtual sound images 7-1 and 7-2 viewed from the listener are input from the positional relationship input means 13. Although the virtual sound images at two locations are used in the present embodiment, the present invention is not limited to this, and processing can be performed using the same processing means even at two or more locations. The filter units 3-1 and 3-2 have IIR in order to realize two virtual sound images as shown in FIG.
Two sets of filter means and arithmetic means are provided in parallel.

According to the positional relationship between the input virtual sound images 7-1 and 7-2, the virtual sound image is generated from the coefficient memory 15 by the controller 14.
The filter coefficient corresponding to 7-1 is applied to the IIR filter means 11-1 and the arithmetic means 12-1 which performs convolution processing, and the virtual sound image 7-2
The filter coefficient corresponding to is set in the IIR filter means 11-2 and the convolution processing means 12-2. The configuration of the IIR filter means 11-1 and 11-2 can be realized by the configuration shown in FIG. 3, similarly to the above-mentioned embodiment. In Fig. 3, a biquad IIR filter is used. 31, 3
2, 33, 34 are delay devices, 35, 36, 37, 38, 3
Reference numeral 9 is a multiplier, and 40 is an adder. In this case, the calculation amount of the IIR filter means 11-1 and 11-2 is equal to the calculation amount of ten plus taps of the FIR filter.

The frequency characteristics (transfer functions) of the IIR filter means 11-1 and 11-2 are the transfer characteristics C1 and C2 (hereinafter, target characteristics C1) of the filter section for realizing the virtual sound images 7-1 and 7-2. , C2
Is called), and the frequencies are set to match at frequencies below the predetermined frequency f0. The predetermined frequency f0 is preferably the lowest resonance frequency of the control speakers 6-1 and 6-2. FIG. 17 shows an example of target characteristics in this embodiment,
FIG. 18A shows an example of the frequency characteristic of the IIR filter means 11-1 for this target characteristic, and FIG. 18B shows an example of the frequency characteristic of the IIR filter means 11-2 for the target characteristic. As can be seen from FIGS. 17 and 18, the frequency characteristics of the IIR filter means 11-1 and 11-2 substantially match the target characteristics C1 and C2 in the range of f0 or less. As a result, in the present embodiment, the low frequency range that could not be controlled without using a large number of taps, in the present embodiment, IIR filter means 11-1, 11
By using -2, you can easily and faithfully reproduce.

The signal filtered by the IIR filter means 11 is input to the arithmetic means 12-1 and the arithmetic means 12-2. The calculation means 12-1 and 12-2 can be configured by FIR filters. FIG. 6 shows an example of the FIR filter forming the calculation means 12-1 and 12-2. 61, 62, 63,
64 is a delay device, 65, 66, 67, 68 are multipliers, 6
9 is an adder. 20A shows an example Cf1 of the frequency characteristic of the calculating means 12-1, and FIG. 20B shows an example Cf2 of the frequency characteristic of the calculating means 12-2. Comparing the target characteristics C1 and Cf1 and C2 and Cf2 in FIGS. 17 and 20, Cf1 is C1 and Cf2 in a region of a predetermined frequency f0 or higher.
It can be seen that reproduces the same frequency characteristics as C2.

FIG. 8 shows an example of the impulse response of the target characteristic, and FIG. 9 shows an example of the impulse response necessary for the calculating means 12-1 in this embodiment. From FIG. 8 and FIG. 9, it is understood that the conventional method requires about 128 taps to realize the frequency characteristic required by the calculating means 12-1, but this embodiment can realize with 32 taps. This is because the characteristics on the low frequency side are realized by the IIR filter means 11.

FIG. 21 shows the calculating means 12-1 of the filter section 3-1.
And an example of the frequency characteristic of the output of the calculating means 12-2 is shown. Figure 2
By comparing 1 with FIG. 17 showing the frequency response of the target characteristic, it can be confirmed that FIG. 17 and FIG. 21 exactly match in the entire frequency band. In other words, by combining the IIR filter means 11 and the arithmetic means 12-1 and 12-2 and adopting a hybrid configuration, the frequency characteristic similar to the conventional method can be realized by the arithmetic means having a smaller number of taps than the conventional method.

The output signals from the filter units 3-1 and 3-2 are input to the D / A converters 4-1 and 4-2, and the output signals of the D / A converter are input to the amplifiers 5-1 and 5-. Enter in 2. By radiating the outputs of the amplifiers 5-1 and 5-2 to a predetermined area by using a control speaker, sound image localization can be realized with virtual sound images as virtual speakers 7-1 and 7-2. .

As described above, the frequency characteristic of the IIR filter means 11 is set as described above, and the IIR filter means 11 and the arithmetic means 12-1 and 12-2 are connected in series to form a hybrid structure. Even if the number of taps of the calculation means is greatly reduced, the transfer characteristic for realizing sound image localization can be accurately realized. Therefore, an accurate control signal can be generated, and the same sound image localization effect as that of the conventional calculation means can be obtained.

When the positions of the virtual sound images 7-1 and 7-2 are located adjacent to each other as seen from the listener 8 as shown in FIG.
The frequency characteristics of the filter means 11-1 and 11-2 are shown in FIGS. 18 (a) and 18 (b) in the frequency region below the predetermined frequency f0.
The characteristics are almost equal. In this case, the IIR filter means 11-1 and 11-2 can be combined into one, and there is no problem in terms of characteristics. Therefore, as shown in FIG.
IIR filter means 11-1 and 11-2 are combined into one to form IIR filter means 11, and the IIR filter means 11 is connected in series with two arithmetic means 12-1 and 12-2 connected in parallel. Replace with the connected configuration. By this replacement, FIG.
It is possible to further reduce the scale of the circuit while maintaining the same frequency characteristic as the configuration including the filter unit including the two IIR filter means shown in FIG.

FIG. 26 shows an example of the determination method of the IIR filter means that can be summarized. In FIG. 26, the predetermined frequency f0
Below, the slope of the frequency characteristic of the IIR filter means is investigated.
It is determined whether or not the slope of the frequency characteristic of the IIR filter means is within a predetermined range from the average value of the slopes of the target characteristics C, and if it is within a predetermined value, the IIR filter means may be put together. In the example of FIG. 26, the predetermined value is ± 6 dB. In the frequency characteristics (a) and (b) of FIG. 26, the inclination of the frequency characteristic of the IIR filter means is within a predetermined range from the average value of the inclination of the target characteristic (a) can be summarized, but it is predetermined. Out of range (b)
Means that they cannot be put together. Although the predetermined value is ± 6 dB in the above determination method, the present invention is not limited to this, and it goes without saying that the predetermined value may be changed depending on the system.

Further, although the present embodiment shows the case of two adjacent virtual sound images that are concentric as viewed from the listener, the present invention is not limited to this and the same processing is performed in all directions. Can be done. Also, when the front of the listener is set to 0 degrees (hereinafter, the angle is based on 0 degrees), a virtual sound image in the range of 45 to 135 degrees or -45 to -135 degrees is realized. If the frequency characteristic of the transfer function is, the characteristic of the IIR filter means 11 is almost the same in the frequency region below the predetermined frequency f0. Also in this case, the IIR filter means 11-1 and 11-2 can be integrated into one as in the above.

Further, in the frequency characteristic of the transfer function for realizing the virtual sound image outside the above range, even when the frequency characteristics of the IIR filter means are equal in the frequency region of a predetermined frequency f0 or less, the IIRs having the same frequency characteristic are the same as above. Filter means can be combined into one.

As described above, by combining a plurality of IIR filter means having substantially the same frequency characteristics in the frequency region of the predetermined frequency f0 or less, the conventional system and the conventional system filter unit are combined. , The size can be further reduced as compared with the case of the above embodiment in which the IIR filter means and the operation means having a tap number shorter than the conventional one are connected in cascade. Especially adjacent angles, and 45 degrees to 135 degrees
Since the frequency response of the transfer characteristic that realizes a virtual sound image in the range of -45 degrees to -135 degrees is almost equal at frequencies below the specified frequency f0, it is possible to combine IIR filter means. is there.

In the present embodiment, the case where the IIR filter means and the arithmetic means are connected in cascade is shown. However, as shown in (Embodiment 2), the IIR filter means and the arithmetic means are connected in parallel. Even if it is used, the same effect can be obtained.

(Embodiment 4) A sound image localization apparatus according to a fourth embodiment of the present invention for simultaneously locating a plurality of virtual sound images symmetrically located on the median plane of a listener will be described with reference to the drawings. The same numbers and symbols are given to those having the same functions as those of the conventional example and (Example 1) (Example 2) (Example 3).

FIG. 22 is an overall block diagram of the sound image localization apparatus of this embodiment, which simultaneously localizes two virtual sound images to the front left and right with the median plane of the listener as the axis of symmetry. In such a case, FIG. 23 is a configuration diagram in which a conventional filter unit is applied, and FIGS. 24 and 25 are block diagrams of the filter unit of this embodiment.

In FIG. 22, except for the configuration and processing of the filter section 3, it is the same as (Example 3). Although the virtual sound images at two locations are used in the present embodiment, the present invention is not limited to this, and processing can be performed using the same processing means even at three or more locations.

In FIG. 23, the filter section 3 has four calculation means 12-1a, 12-2a, and 12-2a, in order to realize two virtual sound images.
12-3a and 12-4a are provided. In FIG. 22, each filter has an arithmetic means 12-1a for h5 (t), an arithmetic means 12-2a for h7 (t), an arithmetic means 12-3a for h6 (t), and an arithmetic means 12-4a. Is configured to realize h8 (t). In the present invention, according to the method shown in (Embodiment 1), the filter section of FIG. 23 is changed to IIR filter means 11-1, 11-2, as shown in FIG.
It can be replaced with 11-3, 11-4 and the arithmetic means 12-1, 12-2, 12-3, 12-4 having a smaller number of taps than the conventional method.

Also in this case, as in (Example 3),
It is possible to combine substantially equivalent IIR filter means into one. However, as shown in FIG. 22, when the virtual sound image is located at a symmetrical position with respect to the median plane of the listener, h5 (t) ≈ h8 (t) h6 (t) ≈ h7 in terms of transfer function. It is known to be (t) (which is generally true).

That is, in this case, the IIR filter means 11-1
And 11-4 and 11-2 and 11-3 are substantially equal. FIG. 25 shows a simplified configuration of the filter section in this case.

As described above, the transfer functions of the filter units output from different control speakers have the predetermined frequency f0.
When the frequency characteristics of the transfer function for realizing the virtual sound image are equal in the following frequency regions, by combining IIR filter means having the same characteristics as shown in FIG. 25,
The hardware scale can be further reduced as compared with the case where the conventional system and the conventional system filter unit are changed to the configuration of the cascade connection of the IIR filter unit and the arithmetic unit having a tap number shorter than the conventional one. Further, as shown in (Example 3), the transfer characteristics for realizing the virtual sound images at the adjacent angles are substantially equal in the frequency region of the predetermined frequency f0 or less, and thus the transfer characteristics are symmetrical with respect to the median plane of the listener. Even when the virtual sound image adjacent to the virtual sound image at the position is realized, the hardware size can be reduced by performing the same processing.

In this embodiment, the IIR filter means and the arithmetic means are connected in cascade. However, as shown in (Embodiment 2), the IIR filter means and the arithmetic means are connected in parallel. The same effect can be obtained by using the above configuration.

[0094]

As described above, according to the present invention, in a system having a hybrid configuration in which the IIR filter means and the computing means are connected in cascade, or a configuration in which they are connected in parallel, the computing means with a smaller number of taps than the conventional one is used. It is possible,
Even with hardware that is smaller in scale than before, it is possible to realize sound image localization equivalent to that in the conventional method. Further, according to the present invention, in a sound image localization apparatus in which a large number of control speakers are arranged, by adopting a configuration in which a plurality of calculation means are connected in parallel and in parallel to one IIR filter means, it is possible to realize a sound image localization equivalent to that in the conventional case. Is. Further, the hardware can be further reduced as compared with the conventional method and the case of using the present invention in the conventional method.

[Brief description of drawings]

FIG. 1 is a block diagram of a sound image localization device according to first and second embodiments of the present invention.

FIG. 2 is a configuration diagram of a filter unit according to a first embodiment of the present invention.

FIG. 3 is a block diagram showing the configuration of IIR filter means of the present invention.

FIG. 4 is a frequency characteristic diagram showing a target characteristic example of the filter unit of the present invention.

FIG. 5 is a frequency characteristic diagram of an example of IIR filter means of the present invention.

FIG. 6 is a block diagram showing a configuration of a computing means of the present invention.

FIG. 7 is a frequency characteristic diagram of an example of the calculating means of the present invention.

FIG. 8 is an impulse characteristic diagram of a conventional calculation means.

FIG. 9 is an impulse characteristic diagram of the arithmetic means of the present invention.

FIG. 10 is a frequency characteristic diagram of an example of the filter unit according to the first embodiment of the present invention.

FIG. 11 is a configuration diagram of a filter unit according to a second embodiment of the present invention.

FIG. 12 is a frequency characteristic diagram of an example of IIR filter means according to the second embodiment of the present invention.

FIG. 13 is a frequency characteristic diagram of an example of a computing means according to a second embodiment of the present invention.

FIG. 14 is a frequency characteristic diagram of an example of the filter unit according to the second embodiment of the present invention.

FIG. 15 is a block diagram of a sound image localization apparatus according to a third embodiment of the present invention.

FIG. 16 is a configuration diagram of a filter unit according to a third embodiment of the present invention.

FIG. 17 is a frequency characteristic diagram showing target characteristic examples of the filter units according to the third and fourth embodiments of the present invention.

FIG. 18 is a frequency characteristic diagram of an example of IIR filter means according to the third embodiment of the present invention.

FIG. 19 is a diagram relating to a filter unit according to a third embodiment of the present invention.

FIG. 20 is a frequency characteristic diagram of an example of a calculating means according to a third embodiment of the present invention.

FIG. 21 is a frequency characteristic diagram of an example of the filter unit according to the third embodiment of the present invention.

FIG. 22 is a block diagram of a sound image localization apparatus according to a fourth embodiment of the present invention.

FIG. 23 is a block diagram of a filter unit in the case where the sound image localization apparatus according to the fourth embodiment of the present invention is configured by a filter unit according to a conventional method.

FIG. 24 is a block diagram of a filter unit in the case where the sound image localization apparatus of the fourth embodiment of the present invention is configured by a filter unit adopting the configuration of (Example 1) to the conventional method.

FIG. 25 is a block diagram of a filter portion of a sound image localization apparatus according to a fourth embodiment of the present invention.

FIG. 26 is a diagram showing criteria of IIR filter means that can be summarized in the present invention.

FIG. 27 is a configuration diagram of a filter unit of a conventional sound image localization device that localizes a plurality of sound images.

FIG. 28 is a configuration diagram of a conventional filter unit.

[Explanation of symbols]

1 Input signal S (t) 2 A / D converter 3-1, 3-2 Signal processing means (filter section) 4-1, 4-2 D / A converter 5-1, 5-2 Amplifier 6-1 , 6-2 Control speakers 7, 7-1, 7-2 Virtual sound image 8 Listeners 11, 11-1, 11-2 IIR filter means 12, 12-1, 12-2, 12-3, 12-4, 12-1a, 12-2a, 12-3a, 12-4a
Convolution calculation means 13 Positional relation input means 14 Coefficient controller 15 Coefficient memory 16 Adder 31, 32, 33, 34 Delay device 35, 36, 37, 38, 39 Multiplier 40 Adder 61, 62, 63, 64 Delay device 65 , 66, 67, 68 Multiplier 69 Adder C, C1 Target characteristics of filter section Cf, Cf1, Cf2 Frequency characteristics of calculation section

─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Shoji Matsumoto 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Riko Ogawa 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (56) References JP-A-5-300597 (JP, A) JP-A-3-106208 (JP, A) JP-A 61-5611 (JP, A) JP-A 58-206300 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04S 7/00 H04S 1/00 H03H 17/04 611 H03H 17/06 611

Claims (31)

(57) [Claims] 1. A positional relationship input means for inputting a positional relationship between a listener and a virtual sound image, and control for receiving a digital acoustic signal and localizing a virtual sound image at the position based on the positional information from the positional relationship input means. A filter unit that outputs a signal,
A D / A converter that converts the output signal from the filter unit into an analog signal, an amplifier that amplifies the output of the D / A converter, and a control that radiates the control signal amplified by the amplifier to a predetermined region. Oh by the sound image localization apparatus that includes a speaker
Thus, the filter unit receives the position information of the virtual sound image and applies it to the first frequency region.
And IIR filter means for outputting a predetermined first processing signal and filtered by the frequency characteristic (a) that receives the first processed signal, the first processed signal and to said first frequency range On the other hand, the second frequency in the high range
And a calculation means for performing a convolution process with a transfer function having a predetermined frequency characteristic (b) for the region and outputting a second processed signal, wherein the predetermined frequency characteristic (a) and the predetermined frequency characteristic ( b) is determined based on the position information of the virtual sound image,
A sound image localization apparatus comprising at least two sets of the filter unit, the D / A converter, the amplifier, and the control speaker. 2. The predetermined frequency characteristic (a) of the IIR filter means substantially coincides with the transfer function between the control speaker for realizing the virtual sound image and the listener in the first frequency region. The sound image localization apparatus according to claim 1. 3. A predetermined frequency characteristic (b) of the arithmetic means.
The sound image localization apparatus according to claim 1, wherein is substantially the same as the transfer function between the control speaker that realizes the virtual sound image and the listener in the second frequency region. 4. The sound image localization apparatus according to claim 2, wherein the first frequency region is a region equal to or lower than the lowest resonance frequency of the control speaker. 5. The sound image localization apparatus according to claim 3, wherein the second frequency region is a region above the lowest resonance frequency of the control speaker. 6. A positional relationship input means for inputting a positional relationship between a listener and a virtual sound image, and a control for receiving a digital acoustic signal and localizing the virtual sound image at the position based on the positional information from the positional relationship input means. A filter unit that outputs a signal,
A D / A converter that converts the output signal from the filter unit into an analog signal, an amplifier that amplifies the output of the D / A converter, and a control that radiates the control signal amplified by the amplifier to a predetermined region. A sound image localization apparatus for locating a virtual sound image , comprising: a speaker , wherein the filter unit receives position information of the virtual sound image and responds to a first frequency region.
And IIR filter means for outputting a first processed signal to filter by a predetermined frequency characteristic (a) that receives the positional information of the imaginary sound image, the first frequency range
Calculating means and said first processed signal and the second for outputting the second processed signal performs convolution processing with a transfer function having a predetermined frequency characteristic (b) for high-frequency of the second frequency range for And a predetermined frequency characteristic (a) and the predetermined frequency characteristic (b) are determined based on the position information of the virtual sound image,
A sound image localization apparatus comprising at least two sets of the filter unit, the D / A converter, the amplifier, and the control speaker. 7. The sum of the predetermined frequency characteristic (a) of the IIR filter means and the predetermined frequency characteristic (b) of the calculation means is a control speaker that realizes the virtual sound image in a first frequency range. The sound image localization apparatus according to claim 6, wherein the transfer function between the sound image localization apparatus and the listener is substantially the same. 8. The sum of the predetermined frequency characteristic (a) of the IIR filter means and the predetermined frequency characteristic (b) of the calculation means is a control speaker for realizing the virtual sound image in a second frequency range. The sound image localization apparatus according to claim 6, wherein the transfer function between the sound image localization apparatus and the listener is substantially the same. 9. The sound image localization apparatus according to claim 7, wherein the first frequency region is a region equal to or lower than the lowest resonance frequency of the control speaker. 10. The sound image localization apparatus according to claim 8, wherein the second frequency region is a region above a minimum resonance frequency of the control speaker. 11. A control for inputting a positional relationship between a listener and a virtual sound image, and a control for receiving a digital acoustic signal and localizing the virtual sound image at the position based on the positional information from the positional relationship input means. A filter unit that outputs a signal, a D / A converter that converts the output signal from the filter unit into an analog signal, an amplifier that amplifies the output of the D / A converter, and a control signal amplified by the amplifier. was a control speaker for radiating a predetermined area, a sound image localization apparatus for localizing a plurality of imaginary sound image, wherein the filter unit receives the positional information of the imaginary sound image, against a first frequency range
And IIR filter means for outputting a predetermined first processing signal and filtered by the frequency characteristic (a) that receives the first processed signal, the first processed signal and to said first frequency range On the other hand, the second frequency in the high range
Computation means for performing convolution processing with a transfer function having a predetermined frequency characteristic (b) for the region and outputting a second processed signal, and an adder for adding all the processed signals of the computing means are provided.
Eteori, the filter section, and said IIR filter means and the operation manual <br/> stage respectively have a number corresponding to the imaginary sound image number, the predetermined frequency characteristic (a) and the predetermined frequency characteristic ( b) is a sound image localization device which is determined based on position information of a virtual sound image, and is provided with at least two sets of the filter unit, the D / A converter, the amplifier, and the control speaker. 12. The predetermined frequency characteristic (a) of the IIR filter means substantially coincides with a transfer function between a control speaker that realizes the virtual sound image and a listener in a first frequency range. The sound image localization device according to claim 11. 13. A predetermined frequency characteristic (b) of the arithmetic means.
12. The sound image localization apparatus according to claim 11, wherein is substantially equal to the transfer function between the control speaker that realizes the virtual sound image and the listener in the second frequency region. 14. The sound image localization apparatus according to claim 12, wherein the first frequency region is a region equal to or lower than a minimum resonance frequency of the control speaker. 15. The sound image localization apparatus according to claim 13, wherein the second frequency region is a region equal to or higher than the lowest resonance frequency of the control speaker. 16. A control for inputting a positional relationship between a listener and a virtual sound image, and a control for receiving a digital acoustic signal and localizing the virtual sound image at the position based on the positional information from the positional relationship input means. A filter unit that outputs a signal, a D / A converter that converts the output signal from the filter unit into an analog signal, an amplifier that amplifies the output of the D / A converter, and a control signal amplified by the amplifier. was a control speaker for radiating a predetermined area, a sound image localization apparatus for localizing a plurality of imaginary sound image, wherein the filter unit receives the positional information of the imaginary sound image, against a first frequency range
And IIR filter means for outputting a predetermined first processing signal and filtered by the frequency characteristic (a) that receives the first processed signal, the first processed signal and to said first frequency range On the other hand, the second frequency in the high range
Computation means for performing convolution processing with a transfer function having a predetermined frequency characteristic (b) for the region and outputting a second processed signal, and an adder for adding all the processed signals of the computing means are provided.
For example, the filter unit is equivalent to the arithmetic means to the imaginary sound image number
And the IIR filter means has one or more and at most one less than the number corresponding to the virtual sound image, and the predetermined frequency characteristic (a) and the predetermined frequency characteristic (b) are the virtual sound image. A sound image localization apparatus, which is defined based on position information and includes at least two sets of the filter unit, the D / A converter, the amplifier, and the control speaker. 17. A method for setting a filter used in a sound image localization apparatus according to claim 16, wherein the frequency characteristic (a) of the IIR filter means is set in a first frequency range.
The frequency characteristics of the transfer function that realizes the virtual sound image of the first angle and the transfer characteristics that realize all the virtual sound images arranged in a predetermined range around the virtual sound image of the first angle substantially match. A filter setting method characterized by setting as follows. 18. The predetermined range has a virtual sound image arranged within the predetermined range with respect to the virtual sound image at the first angle.
18. The filter setting method according to claim 17, wherein the range is adjacent to a predetermined position on a concentric circle centered on the listener. 19. The filter setting method according to claim 18, wherein the predetermined position is within a range of an angle difference of 30 degrees or less viewed from a listener with respect to the virtual sound image of the first angle. 20. A method of setting a filter used in the sound image localization apparatus according to claim 16, wherein the frequency characteristic (a) of the IIR filter means is set in a first frequency range.
The frequency characteristic of the transfer characteristic for realizing all virtual sound images in the range of the second angle is set so as to substantially match the transfer characteristic for realizing any virtual sound image in the range of the second angle. A filter setting method characterized in that 21. The range of the second angle is in the range of 45 degrees to 135 degrees, or -4, when the front side of the listener is 0 degrees.
3. The range from 5 degrees to -135 degrees.
Filter setting method described in 0. 22. The filter setting method according to claim 17, wherein the first frequency region is a region equal to or lower than a minimum resonance frequency of the control speaker. 23. A predetermined frequency characteristic (b) of the arithmetic means.
17. The sound image localization apparatus according to claim 16, wherein is substantially the same as the transfer function between the control speaker that realizes one virtual sound image and the listener in the second frequency region. 24. The sound image localization apparatus according to claim 23, wherein the second frequency region is a region equal to or higher than the lowest resonance frequency of the control speaker. 25. A positional relationship input means for inputting a positional relationship between a listener and a virtual sound image, and a control for receiving a digital acoustic signal and localizing the virtual sound image at the position based on the positional information from the positional relationship input means. A filter unit that outputs a signal, a D / A converter that converts the output signal from the filter unit into an analog signal, an amplifier that amplifies the output of the D / A converter, and a control signal amplified by the amplifier. Is a sound image localization device that localizes a plurality of sound images , the filter unit receiving position information of a virtual sound image and corresponding to a first frequency region.
And IIR filter means for outputting a first processed signal to filter by a predetermined frequency characteristic (a) that receives the first processed signal, the first processed signal and the first frequency domain Second frequency higher than
Performs convolution processing with a transfer function having a predetermined frequency characteristic (b) for the area, the number of calculation means for outputting a second processed signal, collectively processed signal of the operation means corresponds to the number of control speaker and an adder for output only, the filter unit, said arithmetic means and having a number corresponding to the product of the control speaker and the imaginary sound image number, from the number of two or more most computing means the IIR filter means 1 Small number
With the number of loudspeakers controlling the adder
And, connecting said adder and said calculating means and the IIR filter means, said calculating means is connected to any one of the IIR filter means, also of any one output thereof
Wherein is connected to the adder, each adder is inputted an output of the same number of the <br/> calculation means, the predetermined frequency characteristic (a) and the predetermined frequency characteristic (b) is an imaginary sound image A sound image localization device that is defined based on the position information of 1. and includes at least two sets of the D / A converter, the amplifier, and the control speaker. 26. A method of setting a filter used in the sound image localization apparatus according to claim 25, wherein the frequency characteristic (a) of the IIR filter means is in the first frequency range.
The frequency characteristic of the transfer characteristic that realizes the virtual sound image of the first angle realizes all the virtual sound images in the desired range of the second angle symmetrical to the virtual sound image of the first angle with respect to the median plane of the listener. The filter setting method is characterized in that it substantially matches the frequency characteristic of the transfer characteristic. 27. The desired range is a range located on a concentric circle centered on a listener with respect to the virtual sound image of the second angle and adjacent to the virtual sound image of the second angle. How to set the described filter. 28. The filter setting method according to claim 27, wherein the adjacent range is a range in which an angle difference viewed from a listener with respect to the virtual sound image of the second angle is within 30 degrees. 29. The filter setting method according to claim 26, wherein the first frequency region is a region equal to or lower than a minimum resonance frequency of the control speaker. 30. A predetermined frequency characteristic (b) of the arithmetic means.
26. The sound image localization apparatus according to claim 25, wherein is substantially the same as the transfer function between the control speaker that realizes one virtual sound image and the listener in the second frequency region. 31. The sound image localization apparatus according to claim 30, wherein the second frequency region is a region equal to or higher than the lowest resonance frequency of the control speaker.