JP2009260689A - Sound reproducing device, and sound reproducing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow a sound reproducing device having high directivity such as a parametric speaker to perform phase control with simple configuration. <P>SOLUTION: An AD converter 10 samples a modulation signal for amplitude-modulating an ultrasonic signal at a predetermined sampling frequency to generate samples of the modulation signals successively. The successively generated samples of the modulation signal are stored in a storage section 20. A readout section 30 reads a plurality of samples, having predetermined time intervals, among the samples of the modulation signal from the storage section 20. An ultrasonic signal oscillator 40 oscillates an ultrasonic signal. A plurality of amplitude modulators 61, ..., 6n amplitude-modulate the ultrasonic signal by using the plurality of read samples respectively to output a plurality of modulated signals. A plurality of electroacoustic transducers 71, ..., 7n are driven with the plurality of modulated signals respectively. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technique for arbitrarily setting an arrival direction of sound perceived by a listener in a parametric speaker or the like that generates an audible sound having strong directivity using ultrasonic waves.

The sound field control device described in Patent Document 1 applies an ultrasonic signal amplitude-modulated with a modulation signal having an audible frequency to a plurality of ultrasonic elements mounted on an electroacoustic transducer, and from each ultrasonic element. The emitted ultrasonic wave is demodulated by a spatial demodulation action to generate an audible sound corresponding to the modulation signal. At that time, a plurality of phase controllers set the arrival direction of the sound perceived by the listener in an arbitrary direction by controlling the phase of the modulation signal for amplitude modulating the ultrasonic signal for each ultrasonic element. .
JP 2003-143686 A

  The sound field control device described in Patent Document 1 requires a plurality of phase controllers, and has a problem that a large amount of computation is required for phase control.

  In view of the above problems, an object of the present invention is to provide an acoustic generation device and an acoustic reproduction method that arbitrarily set the direction of arrival of sound perceived by a listener with a smaller amount of computation.

  According to one aspect of the present invention, an AD converter samples a modulation signal for amplitude-modulating an ultrasonic signal at a predetermined sampling frequency, and sequentially generates samples of the modulation signal. Sequentially generated modulation signal samples are stored in the storage unit. The reading unit reads a plurality of samples having a predetermined time interval from the samples of the modulation signal from the storage unit. An ultrasonic signal oscillator oscillates an ultrasonic signal. A plurality of amplitude modulators amplitude-modulate the ultrasonic signal using the read plurality of samples, respectively, and output a plurality of modulated signals. A plurality of electroacoustic transducers are respectively driven by a plurality of modulated signals.

  The readout unit reads out a plurality of samples having a predetermined time interval from the storage unit in which the samples of the modulation signal are stored, so that the phase can be controlled with a smaller amount of computation and is perceived by the listener. The direction of arrival of the sound to be played can be arbitrarily set.

  Embodiments of the present invention will be described with reference to the drawings. The same parts are denoted by the same reference numerals, and redundant description is omitted.

  As illustrated in FIG. 1, the sound reproducing device of the first embodiment includes an AD converter 10, a storage unit 20, a reading unit 30, an ultrasonic signal oscillator 40, an AD converter 50, amplitude modulators 61,. Electroacoustic transducers 71,..., 7n and a shift unit 80 are included. Moreover, the sound reproduction method of Example 1 performs each process illustrated in FIG.

  As shown in FIG. 5, the electroacoustic transducers 71,..., 7n are arranged on the same plane so that the distance between adjacent electroacoustic transducers is d. Listeners for the vertical direction of the plane on which the electroacoustic transducers 71,..., 7n are arranged (generally speaking, the direction perpendicular to the wavefront of the ultrasonic waves emitted from the electroacoustic transducers 71,..., 7n). The direction of arrival of the sound perceived by B is defined as θ (−90 ° ≦ θ ≦ 90 °).

  The sound generated from the sound source X in the direction of arrival θ is d at two points P1 and P2 separated by a distance d between the plane where the electroacoustic transducers 71,..., 7n are arranged and a plane parallel to the plane. * The phase is shifted by sin θ / c. c is the speed of sound. Therefore, in order to make the listener B perceive that sound is generated from the sound source X in the direction of arrival θ, the modulated signals among the modulated signals output from the electroacoustic transducers 71,. What is necessary is just to shift the phase of a component by the time interval of dxsin (theta) / c sequentially.

  First, a case where 0 ° ≦ θ ≦ 90 ° is described. The modulation signal is input to the AD converter 10 (see FIG. 1). The modulation signal is a signal for amplitude-modulating the ultrasonic signal oscillated by the ultrasonic signal oscillator 40, and has an audible frequency (a frequency of about 20 Hz to about 20 kHz). The AD converter 10 samples the modulation signal at a predetermined sampling frequency fs, and sequentially generates samples of the modulation signal (step S11). The sampling frequency fs is set to a frequency in the range of 60 kHz to 350 kHz, for example. Hereinafter, when simply referred to as a sample, in principle, it means a sample of a modulation signal.

The generated modulation signal sample is stored in the storage unit 20. In this example, n is the number of electroacoustic transducers 71,..., 7n, and the storage unit 20 has (n−1) × L ₀ +1 storage areas 1,..., (N−1) × L ₀ +1. The generated modulation signal samples are stored in the storage area 1 of the storage unit 20. Here, L ₀ is a storage area number interval corresponding to the time interval d × sin θ / c. Specifically, L ₀ is L ₀ = f (fs · d · sin θ / c), where f (·) is a function that outputs an integer by rounding down or rounding up to the next decimal place. Each sample of the modulated signal read from the storage area having the interval numbered L ₀ has an approximately time interval d × sin θ / c.

The shift unit 80 sequentially moves the samples stored in the plurality of storage areas 1,..., (N−1) × L ₀ +1 to other storage areas (step S2a). In this example, the shift unit 80 sets i as an integer of 1 ≦ i ≦ (n−1) × L ₀ every time a sample of the modulation signal is generated by the AD converter 10 and stores it in the i th storage area i. The stored sample is moved to the (i + 1) th storage area i + 1. That is, each sample stored in each storage area i moves in the direction of arrow a in FIG. The sample stored in the last storage area (n−1) × L ₀ +1 is overwritten by the sample stored in the storage area (n−1) × L ₀ , thereby disappearing from the storage unit 20. In this manner, the storage unit 20 always stores (n−1) × L ₀ +1 samples of the modulation signal from the newest one. The shift of the sample by the shift unit 80 is performed every time a sample of the modulation signal is generated by the AD converter 10 and before the newly generated sample is stored in the storage area 1.

  The reading unit 30 reads a plurality of samples having a predetermined time interval from the samples of the modulation signal from the storage unit 20 (step S21). Since the samples are periodically shifted by the shift unit 80, a plurality of samples having a predetermined time interval are read out by reading a plurality of samples respectively stored in a plurality of predetermined storage areas (step S2b). The sample can be read out. The plurality of read out samples are sent to amplitude modulators 61,.

Specifically, for example, the reading unit 30 reads a sample stored in the (j−1) × L ₀ + 1st storage area, where j is an integer of 1 ≦ j ≦ n, and performs the jth amplitude modulation. To the device 6j. That is, the reading unit 30 reads a plurality of samples stored in the (j−1) × L ₀ + 1st storage area, where j is an integer of 1 ≦ j ≦ n. Thereby, the reading unit 30 reads a plurality of samples in which the time interval between adjacent samples is about d · sin θ / c.

  The ultrasonic signal oscillator 40 oscillates an ultrasonic signal and sends it to the AD converter 50. The frequency range of the ultrasonic signal is 40 kHz to 120 kHz. The AD converter 50 samples the oscillated ultrasonic signal at a predetermined sampling frequency fs and digitizes it. The digitized ultrasonic signal is sent to each of the amplitude modulators 61,.

  The amplitude modulators 61,..., 6n use the samples received from the reading unit 30 to amplitude-modulate the ultrasonic signals and output a plurality of modulated signals to the electroacoustic transducers 71,.

  The electroacoustic transducers 71, ..., 7n are driven by the modulated signals received from the amplitude modulators 61, ..., 6n, respectively, and emit ultrasonic waves. The emitted ultrasonic wave is demodulated by the spatial demodulation function, and the listener can perceive the component of the modulation signal. Further, in this case, the phase of the modulation signal component of the ultrasonic wave output from the electroacoustic transducer on the electroacoustic transducer 71 side advances, and the arrival of 0 ° ≦ θ ≦ 90 ° is reached to the listener. The direction θ can be perceived.

  In this way, the readout unit 30 can control the phase with a smaller amount of calculation by reading out a plurality of samples having a predetermined time interval from the storage unit 20 in which the modulation signal samples are stored. The arrival direction of the sound perceived by the listener can be arbitrarily set.

When −90 ° ≦ θ ≦ 0 °, the reading unit 30 sets j as an integer of 1 ≦ j ≦ n, stores it in the amplitude modulator 6j, and stores it in the storage area (n−j) × L ₀ +1. The stored sample may be read out and sent.

When −90 ° ≦ θ ≦ 0 °, the generated sample is stored in the storage area (n−1) × L ₀ +1 of the storage unit 20, and the shift unit 80 sets i to 1. As long as ≦ i ≦ (n−1) × L ₀ , the sample stored in the i + 1th storage area may be moved to the ith storage area. In this case, the reading unit 30 reads the samples stored in the storage area (j−1) × L ₀ +1 in the amplitude modulator 6j, where j is an integer of 1 ≦ j ≦ n, as described above. You may send it.

  As a result, the phase of the modulation signal component of the ultrasonic wave output from the electroacoustic transducer 7n side advances, and the arrival direction satisfying −90 ° ≦ θ ≦ 0 ° is set to the listener. θ can be perceived.

  The second embodiment is different from the first embodiment in the storage area of the storage unit 21 in which the generated modulation signal is stored and the storage area of the storage unit 21 from which the reading unit 31 reads samples. In the following, different parts will be described with emphasis, and the common parts are the same as those in the first embodiment, and therefore redundant description will be omitted.

  As illustrated in FIG. 3, the sound reproducing device according to the second embodiment includes an AD converter 10, a storage unit 21, a reading unit 31, an ultrasonic signal oscillator 40, an AD converter 50, amplitude modulators 61,. Electroacoustic transducers 71, ..., 7n are included. Moreover, the sound reproduction method of Example 1 performs each process illustrated in FIG.

First, a case where 0 ° ≦ θ ≦ 90 ° is described. The storage unit 21 has n × L ₀ storage areas. Each time a sample of the modulation signal is generated by the AD converter 10, the generated sample is stored in the storage area 1,..., N × L ₀ of the storage unit 21 in a predetermined order (step S12). . In this example, every time the i-th sample is generated by the AD converter 10 with i as a natural number, the i-th sample is stored in the i mod n × L _0th storage area. Here, for any integer x ₁ , x ₂ , x ₁ mod x ₂ is a remainder modulo x _{1 of} integer x ₂ and is non-negative, that is, 1 ≦ x ₁ mod x ₂ ≦ x ₂ Suppose there is. For example, the generated L ₀ + 1-th sample is stored in the storage area L ₀ +1. Thus, the storage unit 21 is a ring buffer. In order to avoid an increase in processing load caused by an increase in i, i may be returned to a small value when i becomes larger than a predetermined value. For example, i = 0 may be set when i> n × L ₀ .

  The reading unit 31 reads a plurality of samples respectively stored in a plurality of storage areas separated from each other by a predetermined order (step S2c). Thereby, the reading unit 31 can read a plurality of samples having a predetermined time interval (step S22). Reading of the reading unit 31 is performed every time the generated sample is stored in the storage area of the storage unit 21. The plurality of read out samples are sent to amplitude modulators 61,.

In this example, samples stored in a plurality of storage areas separated by L ₀ are read out. Specifically, the reading unit 31 reads samples stored in the i- (j−1) × L ₀ mod n × L _0th storage area, where j is an integer of 1 ≦ j ≦ n, Send to amplitude modulator 6j.

For example, when i = L ₀ +1, that is, after the i = L ₀ +1 th sample is stored in the L ₀ +1 mod n × L ₀ th storage area, as shown in FIG. The sample stored in the storage area L ₀ +1 is sent to the modulator 61, the sample stored in the storage area 1 is sent to the amplitude modulator 62, and the storage area (n−1) is sent to the amplitude modulator 63. The sample stored in × L ₀ +1 is sent, and the sample stored in the storage area 2 × L ₀ +1 is sent to the amplitude modulator 6n.

  The ultrasonic signal oscillator 40 oscillates an ultrasonic signal and sends it to the AD converter 50. The frequency range of the ultrasonic signal is 40 kHz to 120 kHz. The AD converter 50 samples the oscillated ultrasonic signal at a predetermined sampling frequency fs and digitizes it. The digitized ultrasonic signal is sent to each of the amplitude modulators 61,.

  The amplitude modulators 61,..., 6n use the samples received from the reading unit 30 to amplitude-modulate the ultrasonic signals and output a plurality of modulated signals to the electroacoustic transducers 71,.

  The electroacoustic transducers 71, ..., 7n are driven by the modulated signals received from the amplitude modulators 61, ..., 6n, respectively, and emit ultrasonic waves. The emitted ultrasonic wave is demodulated by the spatial demodulation function, and the listener can perceive the component of the modulation signal. Further, in this case, the phase of the modulation signal component of the ultrasonic wave output from the electroacoustic transducer on the electroacoustic transducer 71 side advances, and the arrival of 0 ° ≦ θ ≦ 90 ° is reached to the listener. The direction θ can be perceived.

  In this way, the reading unit 31 can control the phase with a smaller amount of calculation by reading a plurality of samples having a predetermined time interval from the storage unit 20 in which the modulation signal samples are stored. The direction of arrival of the sound perceived by the listener can be arbitrarily set.

When −90 ° ≦ θ ≦ 0 °, the reading unit 31 sets j as an integer of 1 ≦ j ≦ n, and stores the storage area i− (n−j) × L _{0 in the} amplitude modulator 6j. it may send read the samples stored in the mod n × L _0.

Further, when −90 ° ≦ θ ≦ 0 °, the generated sample may be stored in the storage area n × L ₀ −i + 1 mod n × L ₀ of the storage unit 21. In this case, the reading unit 31 sets j as an integer of 1 ≦ j ≦ n, and a plurality of pieces of data stored in n × L ₀ −i + 1 + (j−1) × L ₀ mod n × L _0th storage areas, respectively. Read the sample. Then, the sample stored in the n × L ₀ −i + 1 + (j−1) × L ₀ mod n × L _0th storage area is sent to the amplitude modulator 6j.

  As a result, the phase of the modulated signal component of the modulated signal output from the electroacoustic transducer on the electroacoustic transducer 7n side advances, and the direction of arrival θ satisfying −90 ° ≦ θ ≦ 0 ° is set to the listener. Can be perceived.

[Modifications, etc.]
In the first embodiment, (n−1) × L ₀ +1 or more storage areas may be provided. In this case, the _{(n-1) × L 0} +1 or more of the storage area of _{(n-1) × L 0} +1 pieces of the storage regions may be used as described above. Similarly, in the second embodiment, ₀ or more storage areas n × L may be provided.

In the electroacoustic transducers 71,..., 7n, the interval between the adjacent electroacoustic transducers may not be d, and may not be arranged on the same plane. In this case, the time interval between the plurality of samples read by the reading units 30 and 31 is the time for the sound to reach the electroacoustic transducers 71,..., 7n, respectively, assuming that the sound is generated from the sound source X. What is necessary is just an interval. For example, the sound generated from the sound source X is the electro-acoustic transducer 71, ..., _t 1 the time that has reached each 7n, _..., and _{t n (t 1 <... <} t n). In this case, assuming that j is an integer of 1 ≦ j ≦ n−1, the time interval between the sample sent to the amplitude modulator 6j and the sample sent to the amplitude modulator 6j + 1 is about t _{j + 1} −t _j. The reading units 30 and 31 read samples from the storage units 20 and 21, respectively. The storage areas to be read by the reading units 30 and 31 are determined so that such samples can be read, and the samples are read from the determined storage areas.

  Each of the electroacoustic transducers 71,..., 7n may be composed of a plurality of electroacoustic transducers. .., 71a1 and electroacoustic transducer 72 are electroacoustic transducers 721, as exemplified in FIG. ,..., 72a2, the electroacoustic transducer 7j may be composed of electroacoustic transducers 7j1,..., 7jaj, and the electroacoustic transducer 7n may be composed of electroacoustic transducers 7n1,.

  When the above configuration is realized by a computer, the processing contents of the functions of each unit of the sound reproduction device are described by a program. By executing this program on a computer, the functions of the above-described units are realized on the computer.

  That is, the functions of the AD converter 10, the reading units 30 and 31, the ultrasonic signal oscillator 40, the AD converter 50, the amplitude modulators 61,. Are realized. Further, the auxiliary storage device or the memory functions as the storage units 20 and 21.

  The CPU functioning as each unit of the sound reproduction device performs processing on the data read from the memory or the auxiliary storage device, and stores the processed data in the memory or the auxiliary storage device. That is, data is exchanged between the units of the sound reproducing device via the memory or the auxiliary storage device.

The program describing the processing contents can be recorded on a computer-readable recording medium. The computer-readable recording medium may be any medium such as a magnetic recording device, an optical disk, a magneto-optical recording medium, or a semiconductor memory. Specifically, for example, the magnetic recording device may be a hard disk device or a flexible Discs, magnetic tapes, etc. as optical discs, DVD (Digital Versatile Disc), DVD-RAM (Random Access Memory), CD-ROM (Compact Disc Read Only Memory), CD
-R (Recordable) / RW (ReWritable), etc., MO (Magneto-Optical disc), etc. as a magneto-optical recording medium, EEP-ROM (Electronically Erasable and Programmable-Read Only Memory), etc. as a semiconductor memory it can.

  The program is distributed by selling, transferring, or lending a portable recording medium such as a DVD or CD-ROM in which the program is recorded. Furthermore, the program may be distributed by storing the program in a storage device of the server computer and transferring the program from the server computer to another computer via a network.

  As an execution form different from the above-described embodiment, the computer may read the program directly from the portable recording medium and execute processing according to the program. Each time is transferred, the processing according to the received program may be executed sequentially. Also, the program is not transferred from the server computer to the computer, and the above-described processing is executed by a so-called ASP (Application Service Provider) type service that realizes the processing function only by the execution instruction and result acquisition. It is good. Note that the program in this embodiment includes information that is used for processing by an electronic computer and that conforms to the program (data that is not a direct command to a computer but has a property that is based on computer processing).

  In this embodiment, the present apparatus is configured by executing a predetermined program on a computer. However, at least a part of these processing contents may be realized by hardware.

  In addition, the various processes described above are not only executed in time series according to the description, but may be executed in parallel or individually according to the processing capability of the apparatus that executes the processes or as necessary. For example, in FIG. 2, the processing from step S11 to step S2 and the processing of step S3 may be performed in parallel. In FIG. 4, the processing from step S12 to step S2 and the processing of step S3 may be performed in parallel.

  Needless to say, other modifications are possible without departing from the spirit of the present invention.

1 is a functional block diagram of a sound reproduction device according to Embodiment 1. FIG. 2 is a flowchart of a sound reproduction method according to the first embodiment. FIG. 6 is a functional block diagram of the sound reproducing device according to the second embodiment. 10 is a flowchart of the sound reproduction method according to the second embodiment. The figure for demonstrating arrival direction (theta) and time interval dxsin (theta) / c. The functional block diagram of the modification of an acoustic generator.

Explanation of symbols

1,..., N × L ₀ storage area 1,..., (N−1) × L ₀ +1 storage area 10 AD converter 20, 21 Storage section 30, 31 Reading section 40 Ultrasonic signal oscillator 50 AD converter 61, ..., 6n amplitude modulator 71, ..., 7n electroacoustic transducer 80 shift unit

Claims (10)

An ultrasonic signal oscillator for oscillating an ultrasonic signal;
An AD converter that samples a modulation signal for amplitude-modulating the ultrasonic signal at a predetermined sampling frequency and sequentially generates samples of the modulation signal;
A storage unit for storing samples of the modulation signal generated sequentially;
A reading unit for reading a plurality of samples having a predetermined time interval from the samples of the modulation signal from the storage unit;
A plurality of amplitude modulators that amplitude-modulate the ultrasonic signal using each of the plurality of samples and output a plurality of modulated signals;
A plurality of electroacoustic transducers respectively driven by the plurality of modulated signals;
A sound reproducing apparatus including: The sound reproducing device according to claim 1,
The storage unit includes a plurality of storage areas in which samples of the sequentially generated modulation signals are stored,
The sound reproduction device further includes a shift unit that sequentially moves each sample stored in the plurality of storage areas to another storage area,
The reading unit reads a plurality of samples respectively stored in a plurality of predetermined storage areas.
A sound reproducing apparatus characterized by the above. The sound reproducing device according to claim 2,
The direction of arrival of the sound perceived by the listener is θ (−90 ° ≦ θ ≦ 90 °), the interval between adjacent electroacoustic transducers among the plurality of electroacoustic transducers is d, the speed of sound is c, L ₀ = f (fs · d · sin θ / c) as a function of outputting an integer by rounding off or rounding up the fractions of the sampling frequency fs, f (·) · N is the number of storage areas in which the samples of the modulation signal generated sequentially are stored, respectively, (n−1) × L ₀ +1 or more,
Each time a sample is generated by the AD converter, the shift unit converts the sample stored in the i-th storage area with i as an integer of 1 ≦ i ≦ (n−1) × L ₀ to the i + 1-th storage area. The generated sample is stored in the first storage area of the storage unit,
The reading unit reads a plurality of samples respectively stored in the (j−1) × L ₀ + 1st storage area, where j is an integer 1 ≦ j ≦ n.
A sound reproducing apparatus characterized by the above. The sound reproducing device according to claim 1,
The storage unit includes a plurality of storage areas in which samples of the sequentially generated modulation signals are stored,
Each time a sample is generated by the AD converter, the generated sample is stored in a predetermined order in the plurality of storage areas,
The reading unit reads a plurality of samples respectively stored in a plurality of storage areas separated from each other by a predetermined order;
A sound reproducing apparatus characterized by the above. The sound reproducing device according to claim 4,
The direction of arrival of the sound perceived by the listener is θ (−90 ° ≦ θ ≦ 90 °), the interval between adjacent electroacoustic transducers among the plurality of electroacoustic transducers is d, the speed of sound is c, L ₀ = f (fs · d · sin θ / c) as a function of outputting an integer by rounding off or rounding up the fractions of the sampling frequency fs, f (·) · N, and the number of the plurality of storage areas where the sequentially generated modulation signal samples are respectively stored is n × L ₀ or more,
Every time i-th sample is generated by the AD converter, where i is a natural number, the i-th sample is stored in the i mod n × L _0th storage area,
The reading unit reads a plurality of samples stored in the i- (j−1) × L ₀ mod n × L _0th storage area, where j is an integer of 1 ≦ j ≦ n.
A sound reproducing apparatus characterized by the above. An ultrasonic signal oscillation unit for oscillating an ultrasonic signal;
An AD conversion step of sampling a modulation signal for amplitude-modulating the ultrasonic signal at a predetermined sampling frequency, sequentially generating a sample of the modulation signal, and storing the sample in a storage unit;
A step of reading a plurality of samples having a predetermined time interval from the samples of the modulation signal from the storage unit;
An amplitude modulation step of amplitude-modulating the ultrasonic signal using each of the plurality of samples and outputting a plurality of modulated signals;
An electroacoustic conversion step of driving a plurality of electroacoustic conversions with the plurality of modulated signals, respectively;
A sound reproduction method including: The sound reproduction method according to claim 6,
The storage unit includes a plurality of storage areas in which samples of the sequentially generated modulation signals are stored,
The sound reproduction method further includes a shift step of sequentially moving each sample stored in each of the plurality of storage areas to another storage area,
The reading step is a step of reading a plurality of samples respectively stored in a plurality of predetermined storage areas.
An acoustic reproduction method characterized by the above. The sound reproduction method according to claim 7,
The direction of arrival of the sound perceived by the listener is θ (−90 ° ≦ θ ≦ 90 °), the interval between adjacent electroacoustic transducers among the plurality of electroacoustic transducers is d, the speed of sound is c, L ₀ = f (fs · d · sin θ / c) as a function of outputting an integer by rounding off or rounding up the fractions of the sampling frequency fs, f (·) · N is the number of storage areas in which the samples of the modulation signal generated sequentially are stored, respectively, (n−1) × L ₀ +1 or more,
Each time a sample is generated, the samples stored in the i-th storage area with i as an integer of 1 ≦ i ≦ (n−1) × L ₀ in the above shift step are moved to the i + 1-th storage area, respectively. In the AD conversion step, the generated sample is stored in the first storage area of the storage unit,
The reading step is a step of reading a plurality of samples respectively stored in the (j−1) × L ₀ + 1st storage area, where j is an integer of 1 ≦ j ≦ n.
An acoustic reproduction method characterized by the above. The sound reproduction method according to claim 6,
The storage unit includes a plurality of storage areas in which samples of the sequentially generated modulation signals are stored,
The AD conversion step is a step of storing the generated samples in the plurality of storage areas in a predetermined order each time a sample is generated,
The reading step is a step of reading a plurality of samples respectively stored in a plurality of storage areas separated from each other by a predetermined order.
An acoustic reproduction method characterized by the above. The sound reproduction method according to claim 9, wherein
The direction of arrival of the sound perceived by the listener is θ (−90 ° ≦ θ ≦ 90 °), the interval between adjacent electroacoustic transducers among the plurality of electroacoustic transducers is d, the speed of sound is c, L ₀ = f (fs · d · sin θ / c) as a function of outputting an integer by rounding off or rounding up the fractions of the sampling frequency fs, f (·) · N, and the number of the plurality of storage areas where the sequentially generated modulation signal samples are respectively stored is n × L ₀ or more,
The AD conversion step is a step of storing i-th sample in the i mod n × L _0- th storage area every time i-th sample is generated, where i is a natural number.
The reading step is a step of reading a plurality of samples respectively stored in the i- (j−1) × L ₀ mod n × L _0th storage area, where j is an integer of 1 ≦ j ≦ n.
An acoustic reproduction method characterized by the above.

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