JP5997503B2 - Acoustic signal reproduction device - Google Patents

Description

  The present invention relates to an acoustic signal reproduction device, and more particularly to an acoustic signal reproduction device including a speaker array having a plurality of speaker units.

  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 a desired sound image localization (for example, Non-patent document 1). As a speaker array based on the WFS theory, a speaker array in which speaker units are arranged linearly at equal intervals is used. In this case, sufficient sound image localization can be given only for the sound image on the plane formed by the linear speaker array and the listening point. It is also known that the frequency characteristics of the reproduced sound field deteriorate due to interference generated between the speaker units.

A. J. Berkhout, D de Vries, and P. Pogal, Journal of Acoustical Society of America, 93 (1993), p.2764.

  FIG. 5 is a diagram illustrating an example of a sound wave path in the speaker array. Originally, the theory of WFS is applied because the speaker unit exists very closely on the plane, and the distance between the virtual sound source and the speaker array is sufficiently larger than the wavelength of the sound wave, and the wavefront of the sound image to be reproduced Can be regarded as a plane wave. However, in the actual design, the speaker unit forms the speaker array with a certain interval, and in order to clarify the sound image localization, it is effective to bring the virtual sound image closer to the speaker array. In this case, the wavefront of the sound image to be reproduced is a spherical wave, and interference of sound waves in each path from the virtual sound source to the listening position via each speaker unit occurs. FIG. 6 is a diagram illustrating an example of frequency characteristics of an input sound signal and sound output from the speaker array. When the sound wave interference of each path of the speaker array occurs with respect to the input acoustic signal shown in FIG. 6A, a dip occurs in the high frequency band as shown in the frequency characteristic shown in FIG. There is a possibility that the frequency characteristics to be given may be impaired.

7 and 8, the cause of the dip in the frequency characteristics caused by the speaker array will be described in detail. FIG. 7 is a diagram illustrating an example of a path difference of sound waves regarding two speaker units in the speaker array. For example, with respect to the listening position from a virtual sound source, the path length of the sound passing through the two speaker units S1, S2 of the speaker array and L _1, L ₂ respectively. Here, ΔL of the path difference between L ₁ and L ₂ is expressed by Expression (1).

Here, when the path difference ΔL is a half-wave of a certain frequency and an odd multiple of the half-wave, the sound wave of that frequency becomes an opposite phase at the listening position and cancels out. Therefore, if the speed of sound in the air is c, the frequency f _n (n is an integer equal to or greater than 0) that cancels out due to the path difference ΔL can be expressed by Expression (2).

  FIG. 8 is a diagram illustrating an example of a dip of frequency characteristics caused by a path difference. As shown in the figure, 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 occurs for each combination of the speaker units, and the above-described dip also occurs. Therefore, correction by signal processing involves complexity. In particular, in a speaker array in which speaker units are arranged at regular intervals as in the conventional case, regularity is likely to occur in the path difference between the speaker units, and the frequency characteristics are deteriorated by strengthening individual dips due to mutual interference. There was a problem of causing sound quality degradation.

  Accordingly, 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.

In order to solve the various problems described above, an acoustic signal reproducing apparatus according to the present invention, a speaker array having a plurality of speaker units, and at least a portion of the speaker unit is spatially non-uniform arrangement, space The non-uniformly arranged speaker units are spatially non-uniformly arranged by adding a correction value based on an arbitrary random number to the position when the speaker units are regularly arranged . It is characterized by that.

  In addition, it is desirable that all of the speaker units are spatially unevenly arranged.

The case where the speaker units are regularly arranged is preferably a case where the speaker units are arranged at equal intervals .

The plurality of speaker units are preferably arranged in a linear shape, an arc shape, a planar shape, or a window frame shape .

  According to the sound reproducing device of 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.

It is a figure which shows the functional block of the acoustic signal reproducing | regenerating 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 correction value regarding speaker unit arrangement | positioning. It is a figure which shows an example of the change of the frequency characteristic by speaker unit arrangement | positioning. 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 difference of the sound wave in a speaker array. It is a figure which shows an example of the dip of a frequency characteristic.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  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.

  The decoder 10 decodes the input acoustic signal and outputs the decoded acoustic signal to the amplifier 20 as a drive signal. Here, various multi-acoustic sound signals such as 5.1 channel sound used in home theater and digital broadcasting and 22.2 channel sound that is super high-definition sound can be used as the sound signal.

  The amplifier 20 amplifies the drive signal from the decoder 10 and outputs it to each speaker unit of the speaker array 30.

  The speaker array 30 has a plurality of speaker units, and each speaker unit converts the drive signal input from the amplifier 20 into sound and radiates it. The speaker array 30 is not limited to a linear shape, but may be any shape such as an arc shape, a planar shape in which a plurality of arrays are arranged, or a window frame shape along the outer periphery of a display unit such as a liquid crystal display. Is possible.

  The speaker units of the speaker array 30 are spatially unevenly arranged. Here, the spatially non-uniform arrangement means that the speaker units are irregularly arranged as compared with the conventional speaker units arranged at regular intervals. Further, the spatially non-uniform arrangement is not limited to non-uniform intervals between the linearly arranged speaker units, and the horizontal and vertical arrangements may be non-uniform in a plane, This includes a configuration in which the arrangement of the three-dimensional directions of the speaker unit is non-uniform, such as making the arrangement in the depth direction non-uniform. It is also possible to shift the speaker units in different directions. By arranging the speaker units spatially non-uniformly, regularity is unlikely to occur in the sound path difference through each speaker unit, and the sound reproduction quality deteriorates due to the strengthening of the dip of the predetermined frequency characteristics. Can be prevented.

  Of the speaker units of the speaker array 30, at least some of the speaker units can be non-uniformly arranged, or all the speaker units can be non-uniformly arranged. For example, by arranging at least some of the speaker units non-uniformly, the stability of sound image localization is ensured by the regularly arranged speaker units, and a predetermined frequency characteristic is achieved by the non-uniformly arranged speaker units. It can prevent the dip from strengthening each other. Further, by arranging all the speaker units non-uniformly, the dip of the frequency characteristic is dispersed, so that it is possible to improve the frequency characteristic particularly in a high frequency region.

  Each speaker unit can be spatially non-uniformly arranged based on an arbitrary random number. By using a random arrangement based on random numbers in this way, the speaker units can be arranged non-uniformly without performing complicated calculations. Further, the spatially non-uniform arrangement of the speaker units can be realized by adding a correction value based on an arbitrary random number to the positions when the speaker units are arranged at equal intervals. As a result, it is possible to disperse the arrangement of the speaker units and also to distribute the path lengths of the paths passing through the speaker units, thereby ensuring the stability of sound image localization and strengthening the dip of a predetermined frequency characteristic. Can be prevented.

  FIG. 2 is a diagram illustrating an example of the arrangement of speaker units in the speaker array 30. The speaker array 30 in the present embodiment has 41 speaker units, and is arranged so that the intervals between the speaker units are not uniform.

  Here, the speaker array 30 is non-uniformly arranged by adding correction values based on arbitrary random numbers to the positions of the speaker units arranged at equal intervals. For example, when 41 speaker units are uniformly arranged in the range of 2 m at equal intervals, the speaker units are arranged at intervals of 0.05 m. FIG. 3 is a diagram illustrating an example of correction values related to the speaker unit arrangement. As shown in FIG. 3, random correction values distributed in a range of −0.025 m to 0.025 m are applied to each speaker unit, and the speaker arrays arranged at equal intervals are randomized by shifting in the horizontal direction. The speaker array 30 can be arranged in a non-uniform manner.

  FIG. 4 is a diagram illustrating an example of a change in frequency characteristics due to speaker unit arrangement. 4A shows the frequency characteristics of the sound reproduced by the speaker array arranged at equal intervals, and FIG. 4B shows the sound reproduced by the non-uniformly arranged speaker array 30 according to the present embodiment. It is the frequency characteristic. Comparing FIG. 4A and FIG. 4B, it can be seen that the non-uniformly arranged speaker array 30 according to the present embodiment reduces deep dip, particularly in the high frequency band, and improves the frequency characteristics. .

  As described above, 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 unevenly arranged. Thereby, the stability of sound image localization can be secured by the regularly arranged speaker units, and the dip of the predetermined frequency characteristic can be prevented from being strengthened by the non-uniformly arranged speaker units. With the acoustic signal reproduction device 1 according to the present embodiment, the frequency characteristics of the sound image reproduced by the speaker array 30 can be improved while maintaining the localization of the sound image, and higher-quality sound field reproduction is possible. The acoustic signal reproducing apparatus 1 according to the present embodiment can also be applied when reproducing 22.2 channel acoustic signals for Super Hi-Vision with a window frame type speaker array, and can easily reproduce three-dimensional sound in a home environment. It can be.

  Further, all of the speaker units may be arranged spatially non-uniformly. As a result, the frequency characteristic dip is dispersed to improve the frequency characteristic particularly in the high frequency region.

  Further, the speaker units that are spatially non-uniformly arranged may be spatially non-uniformly arranged based on an arbitrary random number. This eliminates the need for a strict calculation process after grasping each path difference due to the non-uniform arrangement, and the arrangement of the speakers can be determined by calculation with less load.

  Also, speaker units that are spatially non-uniformly arranged may be spatially non-uniformly arranged by adding a correction value based on an arbitrary random number to the position when the speaker units are arranged at equal intervals. Good. As a result, it is possible to disperse the arrangement of the speaker units and also to distribute the path lengths of the paths passing through the speaker units, thereby ensuring the stability of sound image localization and strengthening the dip of a predetermined frequency characteristic. Can be prevented.

  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 modifications and corrections 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 a plurality of functional units, steps, and the like can be combined into one or divided.

  For example, in the above embodiment, the correction value is set in the range of -0.025 m to 0.025 m for the speaker unit interval of 0.05 m. For example, the size (for example, diameter) of the speaker unit itself is taken into consideration. Thus, a range from −0.020 m to 0.020 m can be set as a random number range of the correction value. It should be noted that the number of speaker units (41) and the installation width (2 m) in the above embodiment are merely examples, and it goes without saying that the numbers are not limited to these values.

  Further, in the present embodiment, the case where the arrangement of the speaker units is adjusted using the uniformly distributed random number from the equally spaced arrangement is shown, but it is naturally possible to use random numbers according to other statistics such as a normal distribution.

  According to the sound reproducing apparatus of the present invention, there is a usefulness that in a speaker array including a plurality of speaker units, it is possible to reduce deterioration of frequency characteristics due to mutual interference.

DESCRIPTION OF SYMBOLS 1 Sound signal reproducing device 10 Decoder 20 Amplifier 30 Speaker array

Claims (4)

A speaker array having a plurality of speaker units;
At least some of the speaker units are spatially non-uniformly arranged ;
The speaker units that are spatially non-uniformly arranged are spatially non-uniformly arranged by adding a correction value based on an arbitrary random number to the position when the speaker units are regularly arranged . An acoustic signal reproducing apparatus characterized by that.   The sound signal reproducing apparatus according to claim 1, wherein all of the speaker units are spatially non-uniformly arranged. The case where the speaker units are regularly arranged is a case where the speaker units are arranged at equal intervals , according to claim 1 or 2. The acoustic signal reproducing device according to claim 1 , wherein the plurality of speaker units are arranged in a linear shape, an arc shape, a planar shape, or a window frame shape .

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