JP2006191285A - Array speaker system and its audio signal processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an array speaker system for suitably adjusting a phase among speakers, and for enhancing directivity. <P>SOLUTION: This array speaker system 1 is provided with a speaker array 5 where a plurality of arrays 3 are arranged side by side and a delay circuit part 15 for array for delaying audio signals to be output from the plurality of speakers 3 according to the position of each speaker in the speaker array 5 only by delay different for each speaker 3. The delay circuit 15 for array makes the delay amounts of the internal speaker larger than those of the external speaker of the speaker array 5. Also, this array speaker system 1 divides the audio signal into a plurality of frequency bands. The delay circuit part 15 for array varies delay according to the frequency band, and makes the delay larger according as it is the low pass audio signal. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an array speaker system with improved directivity performance.

  Conventionally, an array speaker system in which a plurality of speakers are arranged has been proposed as a speaker system suitable for use in a wide venue such as a live venue or a concert venue. Typically, an array speaker system is composed of a plurality of speakers stacked vertically. Such an array speaker system is disclosed in Patent Document 1, for example.

By the way, in a live venue or the like, it is desirable not to reduce the volume as far as possible, and for that purpose, high directivity is required. Conventionally, in order to increase directivity, single speakers constituting an array speaker system have been mainly improved.
JP 2002-199484 A (page 4-6, FIG. 1)

  However, the conventional array speaker system has a desirable high directivity in a high sound range of 5 to 10 kHz, but has a problem that the directivity is lowered in a lower sound range.

  The present invention has been made to solve the conventional problems, and an object of the present invention is to provide an array speaker system capable of increasing directivity.

  The array speaker system of the present invention includes a speaker array in which a plurality of speakers are arranged side by side, and an audio signal to be output from the plurality of speakers depending on the position of each speaker in the speaker array. The array delay circuit unit delays the audio signal of the speaker closer to the center than the speakers outside the speaker array.

  With this configuration, the phase of the speaker can be suitably adjusted by increasing the delay amount from the outer speaker to the inner speaker, and even if the directivity of the single speaker is the same, Directivity can be improved.

  In the array speaker system of the present invention, the delay circuit section for the array generates a delay amount equivalent to the positional difference between the speakers in the audio output direction in the concave curved speaker arrangement that enhances the directivity of the entire speaker array. With this configuration, the same state as that in which a plurality of speakers are arranged in the shape of the concave curve described above can be obtained, thereby improving directivity.

  In the array speaker system of the present invention, the array delay circuit unit generates a delay amount corresponding to the directivity angle of the speaker alone, the number of speakers of the speaker array, and the speaker interval. With this configuration, it is possible to generate an appropriate delay amount that increases the directivity of the speaker array.

  The array speaker system of the present invention includes frequency dividing means for dividing the audio signal into a plurality of frequency bands, and the array delay circuit section varies the delay amount according to the frequency band. With this configuration, it is possible to adjust the delay characteristics so that the directivity becomes higher for each frequency band, adjust the phase of each frequency band, and obtain high directivity in the entire frequency band.

  In the array speaker system of the present invention, the array delay circuit unit increases the delay amount as the audio signal is lower in the audio signal divided into a plurality of frequency bands. With this configuration, it is possible to improve the directivity in the low sound range while maintaining high directivity in the high sound range.

  The array speaker system of the present invention includes adjusting means for adjusting the delay amount of each speaker in the array delay circuit section for each frequency band. With this configuration, the directivity can be increased by adjusting the delay characteristics while examining the actual directivity.

  Another aspect of the present invention is an audio signal processing device that processes an audio signal output from a speaker array in which a plurality of speakers are arranged in parallel, and this device converts the audio signal into a position of each speaker in the speaker array. The array delay circuit unit delays the speaker by a different delay amount for each speaker, and the array delay circuit unit delays the audio signal of the speaker closer to the center than the speakers outside the speaker array. Also according to this aspect, the directivity of the array speaker system can be improved as described above.

  The audio signal processing apparatus according to the present invention includes frequency dividing means for dividing the audio signal into a plurality of frequency bands, and the array delay circuit unit varies a delay amount according to the frequency bands. This configuration can also improve the directivity of the array speaker system as described above.

  As described above, the present invention provides an array delay circuit unit that delays an audio signal by a different delay amount for each speaker in accordance with the position of each speaker in the speaker array, and has a center compared to the speakers outside the speaker array. By increasing the delay amount of the close speaker, it is possible to provide an array speaker system having an effect that the phase between the speakers can be suitably adjusted and the directivity of the entire speaker array can be improved.

  Hereinafter, an array speaker system according to an embodiment of the present invention will be described with reference to the drawings.

  An array speaker system according to an embodiment of the present invention is shown in FIG.

  In FIG. 1, the array speaker system 1 includes a plurality of speakers 3, and the plurality of speakers 3 are stacked in the vertical direction to form a speaker array 5. In the example of FIG. 1, five speakers 3 are shown. An amplifier 7 is connected to each speaker 3, a plurality of amplifiers 7 are connected to the output side of the audio signal processing device 9, and a mixer 11 is connected to the input side of the audio signal processing device 9. The audio signal processing device 9 supplies the audio signal input from the mixer 11 to each speaker 3.

  The audio signal processing device 9 includes a frequency dividing unit 13, an array delay circuit unit 15, and an equalizer unit 17. The frequency dividing unit 13 divides the input audio signal into signals of a plurality of frequency bands. As will be described later, the array delay circuit unit 15 is configured to delay the audio signal for each speaker and for each frequency band. The equalizer section 17 has a conventional general equalizer configuration.

  The audio signal processing device 9, its equalizer unit 17, and the array delay circuit unit 15 can be realized by a DSP. The audio signal processing device 9 may be realized by adding the function of the array delay circuit unit 15 to the DPS of the conventional equalizer. Further, the audio signal processing device 9 may be incorporated in the mixer 11.

  FIG. 2 shows the configuration of the audio signal processing device 9 together with the amplifier 7 and the speaker 3. The audio signal processing device 9 is roughly provided with a frequency dividing unit 13, an array delay circuit unit 15, and an equalizer unit 17 as shown in FIG. 1, and these are described above from the input side to the output side. Are arranged in order.

  The frequency dividing unit 13 electrically divides the input audio signal into signals of a plurality of frequency bands as described above. In the present embodiment, the audio signal is divided into five bands of 0 to 500 Hz, 500 to 1 kHz, 1 to 2 kHz, 2 to 4 kHz, and 4 to 16 kHz. The frequency division unit 13 includes a plurality of band pass filters.

  The array delay circuit unit 15 includes a plurality of delay circuits 21. The number of delay circuits 21 is the same as the number of speakers 3, and the delay circuits 21 and the speakers 3 are in a one-to-one correspondence. These delay circuits 21 are connected to the frequency division unit 13, and the audio signal divided by the frequency division unit 13 is input to all the delay circuits 21.

  Each delay circuit 21 is further divided as shown in FIG. 2, and is composed of a plurality of delay circuit elements. The plurality of delay circuit elements respectively correspond to a plurality of frequency bands divided by the frequency dividing unit 13, that is, 0 to 500 Hz, 500 to 1 kHz, 1 to 2 kHz, 2 to 4 kHz, and 4 to 16 kHz. Then, signals in a plurality of frequency bands are distributed to the plurality of delay circuit elements and individually delayed.

  In the above configuration, the delay amounts are individually set in the plurality of delay circuits 21, and the delay amounts are individually set for each delay circuit element, that is, for each frequency band. With this configuration, the array delay circuit unit 15 can adjust the phase of the audio signal by varying the delay amount for each speaker and for each frequency band.

  The equalizer unit 17 includes the same number of equalizers 23 as the speakers 3. Each delay circuit 21 is connected to each equalizer 23, and the output side of each equalizer 23 is connected to each speaker 3 via each amplifier 7. With such a configuration, output signals of the plurality of delay circuits 21 are output from a plurality of different speakers 3.

  The audio signal processing device 9 is provided with an adjustment operation unit 25. The adjustment operation unit 25 includes operation members such as buttons, levers, and dials, and is operated by the user to adjust the settings of the array delay circuit unit 15 and the equalizer unit 17. The adjustment operation unit 25 constitutes the adjustment unit of the present invention, and adjusts the delay amount of the array delay circuit unit 15. The delay amount of each delay circuit element of each delay circuit 21 is adjusted according to the operation of the adjustment operation unit 25, whereby the delay amount is adjusted for each speaker and for each frequency band.

  FIG. 3A and FIG. 3B are diagrams for explaining an appropriate delay amount for each speaker. Here, a signal in one frequency band will be described. Schematically, FIG. 3 (a) shows a preferred speaker arrangement with high directivity, and FIG. 3 (b) shows the setting of the delay amount of the array delay circuit section 15, and the array delay is shown. The circuit unit 15 realizes a state equivalent to the speaker arrangement of FIG. 3A by setting the delay amount of FIG.

  First, FIG. 3A shows a speaker arrangement having a concave curve shape. That is, five speakers S1 to S5 are arranged along the concave curve L. The concave curve L is set to increase the directivity of the entire speaker array. The concave curve L is based on the same principle as the parabolic antenna. In a parabolic antenna, as is well known, high directivity can be obtained by configuring the antenna with a curved surface. 3A, a plurality of speakers are arranged along the concave curve L according to the same principle.

  In the speaker arrangement of FIG. 3A, the position of the audio output direction X is different between the speakers, and the speaker position is lowered backward from the outside toward the inside. Specifically, the outer end speakers S1 and S5 are in front, the inner speakers S2 and S4 are behind the speakers S1 and S5, and the central speaker S3 is further rearward. When the positions of the speakers S1 and S5 are used as a reference, the speakers S2, S3, and S4 are located behind the distances d2, d3, and d4 in the audio output direction X, respectively. In this case, d2 = d4 <d3.

  Since the speakers S1 to S5 have such a positional difference in the audio output direction X as described above, a difference also occurs in the arrival time of the sound at a point of the same distance, and the sounds from the speakers S2, S3, and S4 are delayed. If the arrival time differences of the speakers S2, S3, and S4 with respect to the speakers S1 and S5 are t2, t3, and t4, t2 = d2 / V, t3 = d3 / V, and t4 (= t2) = d4 / V. Here, V is the speed of sound.

  The array delay circuit section 15 of the present embodiment realizes the arrival time difference between the speakers in FIG. 3A by adjusting the delay amount.

  That is, in the delay amount setting of FIG. 3B, the delay amount of the inner speaker is made larger than that of the outer speaker of the speaker array, and the delay amount is increased toward the inner speaker. Specifically, as shown in the figure, the delay amounts t1 and t5 of the speakers S1 and S5 at the outer ends are zero. The delay amounts of the speakers S2, S3, and S4 are t2 = d2 / V, t3 = d3 / V, and t4 = d4 / V, respectively, and coincide with the arrival time difference between the speakers described above. In this way, the positional difference between the speakers in the above speaker arrangement is equivalent to the delay amount setting of the present embodiment. Even if the speakers are arranged in a straight line, the same audio output as the above speaker arrangement is realized as the entire speaker array, and high directivity is obtained.

  The delay amount adjustment and the resulting phase adjustment when focusing on one frequency band have been described above.

  Next, with reference to FIG. 4, a preferred delay amount setting according to the frequency band will be described. In general, a loudspeaker alone has a high directivity in the high sound range (high frequency), and the directivity tends to be low as the sound is low (low frequency). Also in the array speaker, if the delay amount adjustment of the present embodiment is not performed, the directivity decreases as the frequency decreases.

  Therefore, it is preferable to increase the delay amount in the array delay circuit unit 15 as the frequency decreases. As a result, the smaller the frequency, the greater the directivity improvement effect by adjusting the delay amount, and therefore the difference in directivity between frequency bands can be reduced.

  Specifically, as shown in FIG. 4, even in the same speaker, the delay amount in the low frequency band is increased. In the present embodiment, the audio signal is divided into five bands of 0 to 500 Hz, 500 to 1 kHz, 1 to 2 kHz, 2 to 4 kHz, and 4 to 16 kHz as described above. The delay amount of the lowest frequency band 0 to 500 Hz is set to the maximum, and the delay amount of the highest frequency 4 to 16 kHz is set to the minimum. In the frequency band of 4 to 16 kHz, the desired directivity can be obtained without the delay amount control, and therefore the delay amount is set to 0 in this embodiment.

  The preferable delay amount setting for each frequency band can also be described using the concave curved speaker arrangement shown in FIG. In FIG. 3A, the concave curve L indicates a speaker arrangement that increases the directivity of the entire speaker array. When trying to obtain the same directivity in different frequency bands, the curvature of the concave curve L varies depending on the frequency band, and the lower the frequency, the greater the depth of the concave when viewed from the front of the array. Therefore, in order to give a delay amount equivalent to the concave curve L to the audio signal, the delay amount may be increased as the frequency is lowered. Therefore, in this embodiment, the delay amount is changed for each frequency band to increase the delay amount in the low band, and thereby, an audio output equivalent to a suitable concave curved speaker arrangement in each frequency band can be obtained. This can be realized and the directivity control is possible by reducing the difference in directivity angle between frequency bands.

  Next, with reference to FIG. 5, the preferred setting of the delay amount described above will be described using mathematical formulas. Here, in order to simplify the explanation, it is assumed that the number of speakers is three.

  FIG. 5 shows a state in which three speakers are arranged along the concave curve described in FIG. 3A. Speakers S1 and S3 are arranged at both ends, and a speaker S2 is arranged at the center. S2 is behind the speakers S1 and S3. In FIG. 5, θ is a directivity angle of a single speaker, a is a distance in the Y direction between adjacent speakers, and d is a distance in the X direction between the speakers S1 and S3 and the speaker S2. Here, the X direction is the audio output direction, and the Y direction is the speaker array direction, which is perpendicular to the audio output X.

  In FIG. 5, the angle θa is an angle formed by the line s 1 -s 2 (a straight line connecting the speakers S 1 and S 2) with respect to the audio output direction X. In order to increase the directivity, it is preferable to set θa = θ. Therefore, d = a / (tan θa) = a / (tan θ). An appropriate delay amount t of the speaker S2 is t = d / V = d / (tan θ) / V (V is the speed of sound).

  Thus, a suitable delay amount in each speaker is determined by the directivity angle of the speaker alone, the number of speakers in the speaker array, and the speaker interval. This is the same when the number of speakers is three or more. That is, the distance in the array direction between the speakers at both ends is determined by the number of speakers and the speaker interval (symbol a in FIG. 5). The distance and the directivity of the speaker alone determine the concave curve of the speaker arrangement that enhances the directivity. The concave curve passes through the speakers at both ends, and its shape changes depending on the directivity. The delay amount is set so that the same audio output state as when the speakers are arranged along such a concave curve is obtained.

  In the above description, the directivity angle is a parameter representing directivity, and is an angle representing a point where the sound volume drops by a predetermined amount at the right and left of the front center of the speaker. The smaller the directivity angle, the higher the directivity. . The definition of the directivity angle is as follows in more detail. In a speaker, the sound pressure on the front axis is generally the highest, and when a circle centering on the speaker (sound source) is drawn, the sound pressure decreases as the distance from the front axis along the circle increases. Here, the intersection of the front axis and the circle is 0 dB. The point where the sound pressure reaches a predetermined amount on the circle and the speaker are connected by a line. The predetermined amount is -6 dB. The angle formed by the −6 dB line with respect to the front axis is the directivity angle. That is, the directivity angle is half of the central angle of the sector region that is -6 dB or more (or the central angle of one side region of the front axis (target axis) in the sector region).

  FIG. 6 shows the delay amount setting when the number of speakers is different. In FIG. 6A, there are four speakers, and in FIG. 6B, there are six speakers. 6 (a) and 6 (b) also assume a concave curved speaker arrangement that enhances directivity, similar to the above-described embodiment. The delay amount of each speaker is adjusted so that the same audio output state as that of the speaker arrangement can be obtained, that is, the arrival time difference between the speakers is the same. The number of speakers is not limited to the example of FIG. 6, and the number of speakers may be larger. Thus, the delay amount control according to the present embodiment can be applied to a speaker array having an arbitrary number of speakers.

  As described above, the preferable delay control has been described using the concave curve and the mathematical expression. The above description shows the principle of improving the directivity of the present embodiment. When adjusting the delay amount in an actual system, the delay amount may be obtained in advance according to the above principle, but this need not be the case. 2 is operated to measure the directivity angle of the speaker array while adjusting the delay amount, and the delay amount of each speaker and each frequency band so that the directivity angle becomes smaller and preferably minimized. May be adjusted.

  Next, the operation of the above-described array speaker system 1 will be described. The audio signal is input from the mixer 11 to the frequency dividing unit 13 of the audio signal processing device 9. In the frequency division unit 13, the audio signal is divided into five bands of 0 to 500 Hz, 500 to 1 kHz, 1 to 2 kHz, 2 to 4 kHz, and 4 to 16 kHz. These audio signals of a plurality of bands are input to all of the plurality of delay circuits 21 of the array delay circuit unit 15.

  In each delay circuit 21, the audio signal of each band is delayed by different delay amounts by separate delay circuit elements. In the array delay circuit unit 15, different delay amounts are given to the audio signal for each speaker and for each frequency in accordance with the delay amount setting as described above.

  The audio signal for each speaker undergoes a delay process, and is further processed by the equalizer 23 for the corresponding speaker, and is output from the audio signal processing device 9. Furthermore, the audio signal for each speaker is output from the corresponding speaker 3 via the amplifier 7 for the corresponding speaker. As a result, the sound generated by the speaker array 5 has a time difference due to the delay processing of the array delay circuit unit 15 between the speakers and between the frequency bands.

  FIG. 7 is a schematic diagram showing the effect of improving directivity according to the present embodiment. In FIG. 7, the horizontal axis represents frequency, and the vertical axis represents the directivity angle. The smaller the directivity angle, the higher the directivity. Here, the target directivity angle is 10 degrees. Line A in the figure shows the directivity characteristics of the speaker array when no delay control is performed. Line B indicates the target directivity in the vertical direction (stack direction). In the line A, the target directivity angle of 10 degrees is achieved only in the high sound range having a frequency of 4 kHz or higher. However, if the frequency is less than 4 kHz, the target directivity angle of 10 degrees is not achieved, and the directivity angle increases as the frequency decreases. On the other hand, in the target directivity characteristic of line B, the directivity angle is set to the target directivity angle in a wider range. According to the present embodiment, the directivity of line A can be brought close to the target directivity of line B by controlling the delay amount between speakers and between frequency bands as described above.

  The array speaker system 1 according to the embodiment of the present invention has been described above. According to the present embodiment, the audio signal of the speaker 3 closer to the center (inner side) than the speakers 3 outside the speaker array is delayed, and the delay amount is increased toward the inner side, so that the phase of each speaker is increased. Even if the directivity of the speaker alone is the same, the directivity in the array direction of the entire speaker array can be improved.

  Further, according to the present embodiment, the speaker array 5 is caused to generate a delay amount equivalent to the position difference between the speakers in the audio output direction in the concave curved speaker arrangement that enhances the overall directivity of the speaker array 5. Thereby, the same state as having arrange | positioned the several speaker 3 in said concave curve shape is obtained, and directivity can be improved.

  Further, according to the present embodiment, a delay amount corresponding to the directivity angle of a single speaker, the number of speakers of the speaker array 5 and the speaker interval is generated in the speaker array 5, whereby the directivity of the speaker array 5 is increased. An appropriate amount of delay can be increased.

  In addition, according to the present embodiment, the audio signal is divided into a plurality of frequency bands, and the delay amount is made different according to the frequency band, thereby delaying the directivity for each frequency band. By adjusting the characteristics, the phase of each frequency band can be adjusted, the directivity can be improved so that a high level of directivity can be obtained, and high directivity can be obtained in the entire frequency range.

  Also, according to the present embodiment, the lower the audio signal divided into a plurality of frequency bands, the lower the audio signal, the higher the directivity of the high frequency range, while increasing the delay amount. The directivity of the entire band can be increased.

  In addition, according to the present embodiment, by providing the adjusting means for adjusting the delay amount of each speaker in the delay circuit for each frequency band, the delay characteristic is adjusted while examining the actual directivity to increase the directivity. it can.

  In the example of FIG. 1, the number of speakers in the speaker array is five. However, as already described, the number of speakers is not limited to this. In the array speaker system, the speaker array does not have to be one row, and two or more speaker arrays may be provided.

  In addition, this invention is not limited to the above-mentioned embodiment, Of course, those skilled in the art can modify the above-mentioned embodiment within the scope of the present invention.

  As described above, the array speaker system according to the present invention has an effect that the directivity of the entire speaker array can be improved by adding different delay amounts to the audio signals for each speaker, and is useful as a speaker for a live venue. It is.

Block diagram of an array speaker system in an embodiment of the present invention The figure which shows the structure of an audio signal processing apparatus (A) The figure which shows the concave-curved speaker arrangement | positioning which raises directivity (b) The figure which shows the delay amount setting which raises directivity Diagram showing different delay settings for each frequency band Diagram for explaining delay amount calculation formula (A) Diagram showing delay amount setting when the number of speakers is four (b) Diagram showing delay amount setting when the number of speakers is six Diagram showing improvement of directivity by delay amount control

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Array speaker system 3 Speaker 5 Speaker array 7 Amplifier 9 Audio signal processing apparatus 11 Mixer 13 Frequency division part 15 Array delay circuit part 17 Equalizer part 21 Delay circuit 23 Equalizer 25 Adjustment operation part

Claims (8)

  A speaker array in which a plurality of speakers are arranged in parallel, and an array delay circuit unit that delays an audio signal to be output from the plurality of speakers by a different delay amount for each speaker according to the position of each speaker in the speaker array The array delay circuit section delays the audio signal of the speaker closer to the center than the speakers outside the speaker array.   2. The array delay circuit unit generates a delay amount equivalent to a position difference between speakers in an audio output direction in a concave curved speaker arrangement that enhances directivity of the entire speaker array. Array speaker system.   The array speaker system according to claim 1, wherein the array delay circuit unit generates a delay amount according to a directivity angle of a single speaker, the number of speakers of the speaker array, and a speaker interval.   4. The frequency division means for dividing the audio signal into a plurality of frequency bands, wherein the array delay circuit unit varies the amount of delay according to the frequency band. Array speaker system.   5. The array speaker system according to claim 4, wherein the array delay circuit unit increases a delay amount as a lower frequency audio signal is divided among a plurality of audio signals.   6. The array speaker system according to claim 4, further comprising adjusting means for adjusting a delay amount of each speaker in the array delay circuit section for each frequency band. An audio signal processing apparatus for processing an audio signal output from a speaker array in which a plurality of speakers are arranged in parallel,
An array delay circuit unit that delays the audio signal by a different delay amount for each speaker in accordance with the position of each speaker in the speaker array, the array delay circuit unit being compared with speakers outside the speaker array; And an audio signal processing apparatus for delaying an audio signal of a speaker closer to the center.   8. The audio signal processing according to claim 7, further comprising frequency dividing means for dividing the audio signal into a plurality of frequency bands, wherein the array delay circuit unit varies a delay amount according to the frequency band. apparatus.

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