close

Вход

Забыли?

вход по аккаунту

?

JP2015008434

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JP2015008434
The present invention reduces degradation of frequency characteristics in a speaker array
including a plurality of speaker units. An acoustic signal reproduction apparatus according to the
present invention includes a speaker array having a plurality of speaker units, and at least a part
of the speaker units are spatially unevenly arranged based on a logistic function. [Selected figure]
Figure 2
Acoustic signal reproduction device
[0001]
The present invention relates to an acoustic signal reproduction apparatus, and more particularly
to an acoustic signal reproduction apparatus including a speaker array having a plurality of
speaker units.
[0002]
A speaker array based on the theory of Wave Field Synthesis (WFS) is used as a technique for
reproducing the physical characteristics of the original sound field using a large number of
speaker units and providing desired sound image localization (for example, Non-Patent
Document 1).
As a speaker array based on the theory of WFS, one in which speaker units are arranged linearly
at equal intervals is used. In this case, sufficient sound image localization can be provided only
07-05-2019
1
for the sound image on the plane formed by the linear speaker array and the listening point.
Moreover, it is also known that the frequency characteristic of the reproduced sound field is
degraded due to the interference generated between the speaker units.
[0003]
A. J. Berkhout, D de Vries, and P. Pogal, Journal of Acoustical Society of America, 93 (1993), p.
2764.
[0004]
FIG. 8 is a diagram showing an example of a sound wave path in the speaker array.
Originally, the WFS theory is applied when the distance between the virtual sound source and the
speaker array is sufficiently larger than the wavelength of the sound wave, and the wave front of
the sound image to be reproduced can be regarded as a plane wave. However, in order to make
the sound image localization clear, it is effective to bring the virtual sound image close to the
speaker array. In this case, the wave front of the sound image to be reproduced is a spherical
wave, and the interference of the sound waves of each path from the virtual sound source to the
listening position via each speaker unit occurs. FIG. 9 is a diagram showing an example of the
frequency characteristics of the input acoustic signal and the sound output from the speaker
array. When interference of sound waves in each path of the speaker array occurs with respect to
the input acoustic signal shown in FIG. 9A, dip occurs in the high frequency band as in the
frequency characteristic shown in FIG. The frequency characteristics to be given may be
impaired.
[0005]
The cause of the dip in the frequency characteristic due to the speaker array will be described in
detail with reference to FIGS. FIG. 10 is a diagram showing an example of a path difference of
sound waves with respect to two speaker units in the speaker array. For example, let L 1 and L 2
be the path lengths of the sound passing through the two speaker units S 1 and S 2 of the
speaker array from the virtual sound source to the listening position, respectively. Here, ΔL,
which is the path difference between L 1 and L 2, is expressed by equation (1).
07-05-2019
2
[0006]
[0007]
Here, when the path difference ΔL is a half wavelength of a certain frequency and an odd
multiple of a half wavelength, the sound waves of the frequency are in opposite phase at the
listening position and cancel each other.
Therefore, assuming that the sound velocity in the air is c, the frequency f n (n is an integer of 0
or more) that cancels out due to the path difference ΔL can be expressed by equation (2).
[0008]
[0009]
FIG. 11 is a diagram illustrating an example of dips in frequency characteristics that occur due to
a path difference.
As illustrated, a dip occurs at the frequency shown in equation (2). Here, since the speaker array
includes a large number of speaker units, a path difference is generated for each combination of
speaker units, and the above-described dips are also generated, so that correction by signal
processing is complicated and difficult. In particular, in the speaker array in which the speaker
units are arranged at equal intervals as in the prior art, regularity easily occurs in the path
difference between the speaker units, and the frequency characteristics deteriorate due to the
individual dips strengthening each other due to mutual interference. There is a problem that the
sound quality is deteriorated.
[0010]
Therefore, an object of the present invention made in view of such a point is to provide a sound
reproducing apparatus capable of reducing deterioration of frequency characteristics due to
mutual interference in a speaker array including a plurality of speaker units.
07-05-2019
3
[0011]
In order to solve the various problems described above, an acoustic signal reproduction
apparatus according to the present invention includes a speaker array having a plurality of
speaker units, and at least some of the speaker units are spatially nonuniformly based on a
logistic function. It is characterized in that it is arranged.
[0012]
Further, it is desirable that all of the speaker units be spatially unevenly arranged.
[0013]
Further, it is preferable that the coefficient of the logistic function is set to 3.5699 or more.
[0014]
According to the sound reproducing apparatus according to the present invention, it is possible
to reduce deterioration of frequency characteristics due to mutual interference in a speaker array
including a plurality of speaker units.
[0015]
It is a figure which shows the functional block of the acoustic signal reproduction apparatus
which concerns on one Embodiment of this invention.
It is a figure which shows an example of arrangement | positioning of the speaker unit in a
speaker array.
It is a figure which shows an example of the frequency characteristic of the speaker array of
equally-spaced arrangement.
It is a figure which shows an example of the frequency characteristic of the speaker array
arrange | positioned by the logistic function whose coefficient is 2.5.
It is a figure which shows an example of the frequency characteristic of the speaker array
07-05-2019
4
arrange | positioned by the logistic function whose coefficient is 3.7.
It is a figure which shows an example of the frequency characteristic of the speaker array
arrange | positioned by the logistic function whose coefficient is 3.9. It is a figure which shows
an example of the frequency characteristic of the speaker array arrange | positioned by the
logistic function whose coefficient is 4.0. It is a figure which shows an example of the path |
route of the sound wave in a speaker array. It is a figure which shows an example of the
frequency characteristic of an input acoustic signal and a speaker array output. It is a figure
which shows an example of the path | route difference of the sound wave in a speaker array. It is
a figure which shows an example of the dip of a frequency characteristic.
[0016]
Hereinafter, embodiments of the present invention will be described in detail with reference to
the drawings.
[0017]
FIG. 1 is a diagram showing functional blocks of an acoustic signal reproduction device 1
according to an embodiment of the present invention.
The acoustic signal reproduction device 1 includes a decoder 10, an amplifier 20, and a speaker
array 30.
[0018]
The decoder 10 decodes the input acoustic signal, and outputs the decoded acoustic signal to the
amplifier 20 as a drive signal. Here, as the sound signal, various multi-sound type sound signals
such as 5.1 channel sound used in home theater and digital broadcasting, 22.2 channel sound
which is super hi-vision sound, etc. can be used.
[0019]
07-05-2019
5
The amplifier 20 amplifies the drive signal from the decoder 10 and outputs it to each speaker
unit of the speaker array 30. Although one amplifier 20 is illustrated in FIG. 1, it is possible to
have a configuration in which each speaker unit is provided with an independent amplifier 20.
[0020]
The speaker array 30 has a plurality of speaker units, and each speaker unit converts a drive
signal input from the amplifier 20 into a sound and emits the sound. The speaker array 30 is not
limited to a linear shape, but may have an arbitrary shape such as an arc shape, a planar shape in
which an array of a plurality of stages is arranged, or a window frame shape along the outer
periphery of a display unit such as a liquid crystal display. Is possible.
[0021]
The speaker units of the speaker array 30 are spatially unevenly arranged. Here, spatially
nonuniformly arranged means that the speaker units are irregularly arranged, as compared to
the conventional equally spaced speaker units. In addition, spatially nonuniformly arranged is not
limited to making the spacing between the linearly arranged speaker units nonuniformly, but
makes the vertical and horizontal arrangements uneven in plan view, and further, It includes a
configuration in which the arrangement in the three-dimensional directions of the speaker unit is
uneven, such as making the arrangement in the depth direction uneven. Moreover, it is also
possible to shift to a different direction for every speaker unit. By arranging the speaker units
spatially unevenly, regularity is less likely to occur in the path difference of the sound passing
through each speaker unit, and deterioration of sound reproduction quality due to strengthening
of dips of predetermined frequency characteristics It can be prevented.
[0022]
Among the speaker units of the speaker array 30, at least a part of the speaker units can be
unevenly arranged, or all the speaker units can be unevenly arranged. For example, by arranging
at least a part of the speaker units nonuniformly, the stability of sound image localization is
ensured by the speaker units arranged regularly, and the speaker units arranged nonuniformly
have predetermined frequency characteristics. It is possible to prevent dips from strengthening
each other. Further, by arranging all the speaker units unevenly, dips of the frequency
characteristic are dispersed, and it is possible to improve the frequency characteristic.
07-05-2019
6
[0023]
Each speaker unit can be spatially unevenly arranged based on arbitrary random numbers. By
using the random arrangement based on the random numbers in this manner, it is possible to
arrange the speaker units unevenly without performing complicated calculations. Here, the
speaker units of the speaker array 30 according to the present embodiment are determined
using a logistic function which is a basic function in chaos theory. The logistic function is
expressed by equation (3) with a as a coefficient.
[0024]
[0025]
When the value of the coefficient a is adjusted, the series of X n shows a monotonous decrease at
a = 0.9, and increases and then peaks at a = 1.5.
When a = 2.5, damped oscillation occurs, and the change of the oscillation period is observed
after that, the period changes according to the value of a, and when it becomes a = 3.5699 or
more, it becomes a phenomenon called chaos and fluctuates complicatedly become. By arranging
the speaker units at non-uniform intervals using the ratio represented by the number sequence X
n using an appropriate coefficient a, it is possible to suppress the degree of peak dip occurring
particularly in the high band above the aliasing frequency and improve the sound quality It is
considered possible. The aliasing frequency indicates a frequency having a wavelength twice as
high as one interval when the speaker units are arranged at equal intervals.
[0026]
FIG. 2 is a view showing an example of the arrangement of speaker units in the speaker array 30.
As shown in FIG. The speaker array 30 in the present embodiment has 32 speaker units in a
range of 2 m.
07-05-2019
7
[0027]
FIG. 3 is a diagram showing frequency characteristics when the speaker units are arranged at
equal intervals in a range of 2 m. As shown in the figure, mutual interference of the speaker units
occurs in a band higher than the aliasing frequency, and the reproduction quality of the sound is
degraded due to the periodic dip (peak dip) of the frequency characteristic.
[0028]
The speaker array 30 in the present embodiment changes the distance between the speaker units
based on the following equation (4). Here, r n is the lateral position of the n-th speaker unit (for
example, -1 m to 1 m), m is the number of speaker units (32), and L is the length of the area
where the speaker units of the speaker array 30 are arranged (For example, 2 m).
[0029]
[0030]
FIG. 4 is a diagram showing frequency characteristics in the case of a = 2.5.
It can be seen that the peak dip from the aliasing frequency to about 8 kHz is suppressed and the
frequency characteristic in the practical sound range is improved as compared with the
frequency characteristic of the equally-spaced arrangement.
[0031]
FIG. 5 is a diagram showing frequency characteristics in the case of a = 3.7. In this case, the peak
dip is suppressed from the aliasing frequency to a high frequency region exceeding 10 kHz. The
coefficient a is 3.5699 or more, and the logistic function is a phenomenon called chaos, and
varies in a complicated manner, so that the intervals of the speaker units become uneven, and the
deterioration of the dip due to mutual interference is eliminated.
07-05-2019
8
[0032]
FIG. 6 is a diagram showing frequency characteristics in the case of a = 3.9. As in FIG. 5, the peak
dip is suppressed from the aliasing frequency to a high frequency region exceeding 10 kHz. The
coefficient a is 3.5699 or more, and the logistic function is a phenomenon called chaos, and
varies in a complicated manner, so that the intervals of the speaker units become uneven, and the
deterioration of the dip due to mutual interference is eliminated.
[0033]
FIG. 7 is a diagram showing frequency characteristics in the case of a = 4.0. In this case, it can be
seen that the peak dip above the aliasing frequency is suppressed. The coefficient a is 3.5699 or
more, and by arranging the intervals of the speaker units with the complexity defined by the
logistic function, the periodicity of mutual interference disappears, and the deterioration of the
dip is suppressed.
[0034]
Thus, according to the present embodiment, the acoustic signal reproduction device 1 includes
the speaker array 30 having a plurality of speaker units, and at least some of the speaker units
are spatially nonuniformly based on the logistic function. It is arranged. As a result, the stability
of sound image localization can be ensured by the speaker units arranged regularly, and the dips
of predetermined frequency characteristics can be prevented from strengthening each other by
the speaker units arranged nonuniformly. In addition, no complicated calculation process is
required for nonuniform placement. Furthermore, by adjusting the coefficient a of the logistic
function, it is possible to set the degree of non-uniformity.
[0035]
Also, all of the speaker units may be spatially unevenly arranged. This makes it possible to
improve the frequency characteristics particularly in the high frequency region by dispersing the
dip of the frequency characteristics.
07-05-2019
9
[0036]
The coefficient a of the logistic function is preferably set to 3.5699 or more. As a result, the
behavior of the logistic function becomes a phenomenon called chaos and fluctuates in a complex
manner, so it is possible to disperse the dip of the frequency characteristic more and to improve
the frequency characteristic particularly in the high frequency region.
[0037]
Although the present invention has been described based on the drawings and examples, it
should be noted that those skilled in the art can easily make various changes and modifications
based on the present disclosure. Therefore, it should be noted that these variations and
modifications are included in the scope of the present invention. For example, functions included
in each functional unit can be rearranged so as not to be logically contradictory, and it is possible
to combine or divide a plurality of functional units or steps into one.
[0038]
ADVANTAGE OF THE INVENTION According to the sound reproduction apparatus which
concerns on this invention, in the speaker array containing several speaker units, there exists a
usefulness that deterioration of the frequency characteristic by mutual interference can be
reduced.
[0039]
1 sound signal reproduction apparatus 10 decoder 20 amplifier 30 speaker array
07-05-2019
10
Документ
Категория
Без категории
Просмотров
0
Размер файла
19 Кб
Теги
jp2015008434
1/--страниц
Пожаловаться на содержимое документа