Sound projection system

Abstract

The present technology pertains to a sound emission system that can make it unlikely to hear sound leaking outside a specified direction. This sound emission system is provided with: at least one first speaker that emits a target sound; and at least one second speaker that is disposed adjacent to the at least one first speaker and that emits a directional concealment sound. The present technology is applicable to a sound emission system.

Description

[Technical Field]

[0001] The present technology relates to a sound emission system, and more particularly to a sound emission system that can make it difficult to hear sounds leaking outside a specified direction. [Background technology]

[0002] For example, when displaying advertisements or other items, there is a need to ensure that sound can only be heard from a position where the display can be seen, so that the surrounding area is not disturbed.

[0003] When sound is emitted using a normal speaker, the emitted sound may be diffused and leak into the surrounding area, making the sound noisy.

[0004] In such cases, it is possible to minimize the diffusion of sound by using a system that forms directivity using a plurality of speakers, such as a line array speaker.

[0005] Line array speakers are a technology already commercially available from various companies, and by arranging multiple speakers in a line, they can form directivity in the vertical direction of the speaker row. Some array-shaped speakers also use signal processing technology to control the directivity.

[0006] Furthermore, a technique for controlling directivity by signal processing using an array speaker has also been proposed (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-115396 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-41023 Summary of the Invention [Problem to be solved by the invention]

[0008] However, even when using a line array speaker and directivity control using signal processing, although a sharp directivity is formed at the center of the line array speaker, the directivity at the edges of the array speaker becomes weaker than at the center, making the sound more likely to diffuse.

[0009] This is because directivity is formed by the interaction of multiple speakers; for example, if a line array speaker is installed horizontally to the ground, there is no speaker at the right end of the line array speaker that can affect the sound that is diffused to the right.

[0010] Due to this principle, when a line array speaker is installed horizontally, sound leaks (diffuses) from the right and left ends.

[0011] The present technology has been made in consideration of such circumstances, and makes it possible to make it difficult to hear sounds leaking outside a specified direction. [Means for solving the problem]

[0012] A sound emission system according to one aspect of the present technology includes one or more first speakers that emit a target sound, and one or more second speakers that are arranged adjacent to the one or more first speakers and emit a directional concealment sound. and a plurality of microphones that pick up environmental sounds in the vicinity of the area where the concealment sound is emitted, and the one or more second speakers emit the concealment sound based on the concealment sound signal selected from a plurality of concealment sound signals obtained based on a plurality of environmental sound signals that have been picked up in advance by the microphones at different timings.

[0013] In one aspect of the present technology, a target sound is emitted by one or more first speakers, and a directional concealment sound is emitted by one or more second speakers arranged adjacent to the one or more first speakers. Environmental sounds in the vicinity of an area where the concealment sound is emitted are picked up by a plurality of microphones, and the one or more second speakers emit the concealment sound based on the concealment sound signal selected from a plurality of concealment sound signals obtained based on a plurality of environmental sound signals previously picked up by the microphones at different timings. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a sound emission system. [Figure 2] FIG. 10 is a diagram illustrating sound leakage. [Figure 3] 10 is a flowchart illustrating a playback process. [Figure 4] FIG. 1 is a diagram illustrating an example of the configuration of a sound emission system. [Figure 5] FIG. 10 is a diagram illustrating sound leakage. [Figure 6] FIG. 1 is a diagram illustrating an example of the configuration of a sound emission system. [Figure 7] FIG. 10 is a diagram illustrating sound leakage. [Figure 8] 10 is a flowchart illustrating a playback process. [Figure 9] 10 is a flowchart illustrating a playback process. [Figure 10] 10A and 10B are diagrams illustrating correction of frequency characteristics of an array speaker. [Figure 11] 10A and 10B are diagrams illustrating correction of the frequency characteristics of a microphone. [Figure 12] FIG. 1 illustrates an example of the configuration of a computer. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments to which the present technology is applied will be described with reference to the drawings.

[0016] First Embodiment <Example of sound output system configuration> (Plays pre-recorded concealed audio) This technology makes it difficult to perceive sound leaking outside the direction of direction in sound emission systems that form directivity using one or more speakers, such as line array speakers.

[0017] With this technology, for example, sound leaking from the end of a line array speaker can be made to sound similar to the sound in the area where the leaking sound is heard, or sound picked up in that area, making it difficult to distinguish from the sound in that area and making it difficult for listeners to sense that the sound is leaking.

[0018] FIG. 1 is a diagram showing an example of the configuration of an embodiment of a sound emission system to which the present technology is applied.

[0019] The sound output system 11 shown in FIG. 1 includes an audio player 21-1, an audio player 21-2, an audio player 22, an audio amplifier 23-1, an audio amplifier 23-2, an audio amplifier 24, an array speaker 25-1, an array speaker 25-2, and an array speaker 26.

[0020] In the audio player 21-1 and the audio player 21-2, a masking sound signal, which is an audio signal of a pre-recorded environmental sound, is recorded. Here, the pre-recorded environmental sound is used as a masking sound to make sound leakage less perceptible.

[0021] The audio reproducers 21-1 and 21-2 start reproducing audio in response to a reproduction start signal or button operation (not shown), and output analog or digital concealment sound signals to the audio amplifiers 23-1 and 23-2.

[0022] The audio amplifiers 23-1 and 23-2 amplify the concealment sound signals supplied from the audio reproducers 21-1 and 21-2, and drive the array speakers 25-1 and 25-2 based on the amplified concealment sound signals to emit the concealment sounds.

[0023] In the following description, when there is no need to particularly distinguish between the audio player 21-1 and the audio player 21-2, they will also be simply referred to as the audio player 21.

[0024] Furthermore, hereinafter, when there is no need to particularly distinguish between the audio amplifiers 23-1 and 23-2, they will be simply referred to as audio amplifiers 23, and when there is no need to particularly distinguish between the array speakers 25-1 and 25-2, they will be simply referred to as array speakers 25.

[0025] The audio player 22 stores a target sound signal, which is an audio signal of a target sound such as a pre-recorded explanation of an advertisement to be displayed. The target sound here is a sound that is desired to be heard by the listener.

[0026] The audio player 22 starts playing audio in response to a playback start signal or button operation (not shown), and outputs an analog or digital target sound signal to the audio amplifier 24 .

[0027] The audio amplifier 24 amplifies the target sound signal supplied from the audio player 22, and drives the array speaker 26 based on the amplified target sound signal to emit the target sound.

[0028] For example, the array speaker 25 and the array speaker 26 each include 16 speakers (speaker units) arranged at equal intervals in the horizontal direction.

[0029] Here, the array speaker 25-1 and the array speaker 25-2 are arranged at different ends of the array speaker 26, that is, adjacent to each other at the left and right ends.

[0030] Furthermore, the speakers that make up the array speaker 25 and the array speaker 26 are arranged in a straight line, i.e., at equal intervals in the horizontal direction. Therefore, in this example, 16 × 3 speakers are arranged in a straight line at equal intervals.

[0031] Although an example will be described here in which the array speaker 26 made up of a plurality of speakers is used as a speaker for emitting the target sound, only one speaker may be used to emit the target sound.

[0032] Similarly, although an example in which the array speaker 25 is used as a speaker that emits the concealment sound will be described here, the number of speakers used to emit the concealment sound may be one. In such a case, however, it is preferable to emit the concealment sound using a speaker having directionality so that the concealment sound has the desired directivity.

[0033] Furthermore, some speakers on the array speaker 26 side of the array speaker 25 may be used to emit not only the concealed sound but also the target sound. Similarly, some speakers on the array speaker 25 side of the array speaker 26 may be used to emit not only the target sound but also the concealed sound.

[0034] Next, with reference to Fig. 2, we will explain sound leakage that occurs when line array speakers or the like are used as the array speakers 25 and 26. In Fig. 2, parts that correspond to those in Fig. 1 are given the same reference numerals, and their explanation will be omitted where appropriate.

[0035] In the example of Figure 2, for example, concealment sound A is emitted from array speaker 25-1, audio such as an explanation of the advertisement to be displayed, i.e., target sound, is emitted from array speaker 26, and concealment sound B is emitted from array speaker 25-2.

[0036] Furthermore, when sound is emitted from the array speaker 25-1, the area where the sound can be heard most clearly due to the directivity of the sound, that is, the area where the sound pressure level is high, is defined as area R11.

[0037] In other words, the array speaker 25-1 outputs the concealment sound A having directionality so that the concealment sound A can be heard basically only within the region R11.

[0038] Here, the output (emission) of the directional concealment sound A is realized by forming the directionality using, for example, a line array speaker or a directional speaker as the array speaker 25-1, or by wave field synthesis, which synthesizes the wave fields of the sounds from each speaker that makes up the array speaker 25-1.

[0039] Furthermore, when sound is emitted from the array speaker 26, the area where the sound can be best heard due to the directivity of the sound is designated as area R12, and when sound is emitted from the array speaker 25-2, the area where the sound can be best heard due to the directivity of the sound is designated as area R13.

[0040] That is, for example, the array speaker 26 outputs a target sound having directivity so that the target sound can basically be heard only within the region R12.

[0041] For example, the emission of a directional target sound may be realized by forming directivity using a line array speaker or a directional speaker as the array speaker 26, or by wave field synthesis, etc. Note that the target sound does not necessarily have to be directional.

[0042] Similarly to the array speaker 25-1, the array speaker 25-2 also emits directional concealment sound B. In this case, the concealment sound B can be made directional by forming directivity using a line array speaker or a directional speaker as the array speaker 25-2, or by wave field synthesis.

[0043] As described above, the target sound emitted from the array speaker 26 leaks into the region R11 and the region R13 at the left and right ends of the array speaker 26, i.e., near the boundary between the region R12 and the region R11 and near the boundary between the region R12 and the region R13. In other words, sound leakage occurs.

[0044] The target sound leaking out in this way is heard overlapping with the concealed sound A emitted by the array speaker 25-1 in, for example, the area R11.

[0045] When a listener hears these overlapping sounds, the influence of the masking sound A makes it difficult for the listener to notice (perceive) the sound leakage of the target sound, that is, the diffusion of the target sound.

[0046] For example, auditory masking occurs due to the influence of overlapping masking sounds caused by a characteristic of the human ear known as the auditory masking effect, making it difficult to notice sound leakage.

[0047] Furthermore, the auditory masking effect can be enhanced by analyzing the frequency of the target sound and equalizing the frequency of the concealment sound A so as to conceal (mask) the frequency peak based on the principle of auditory masking.

[0048] Furthermore, if the target sound is frequency-analyzed and a sound that destroys its characteristics is superimposed on the concealment sound A and emitted, the leaking target sound can be made unclear, making it difficult for the listener to notice the leaking target sound.

[0049] Here, destroying the characteristics of the target sound means that when the target sound and a sound that destroys the characteristics of the target sound are played back simultaneously, the target sound sounds unclear, that is, the target sound is difficult to hear as meaningful sound. In other words, a sound that destroys the characteristics of the target sound is a sound that has frequency characteristics that cancel out the characteristics of the target sound.

[0050] Therefore, for example, a sound that destroys the characteristics of the target sound should have a large frequency component in the downward peaks (valleys) in the frequency waveform (spectrum) of the target sound, and when the target sound is synthesized, the frequency waveform of the synthesized sound should be roughly flat.

[0051] Such methods of generating speech that destroys certain speech characteristics are described in detail in, for example, "Akagi Masato and Irie Yoshihiro, 'Privacy protection for speech based on concepts of auditory scene analysis,' Technical Research Report of the Institute of Electronics, Information and Communication Engineers, Applied Acoustics 111(333), 19-24, 2011-12-02."

[0052] Note that, although the above has explained the relationship between the target sound emitted toward area R12 and the concealment sound A emitted toward area R11, the same can be said for the relationship between the target sound emitted toward area R12 and the concealment sound B emitted toward area R13.

[0053] Next, sound leakage of the concealment sound A emitted into the region R11 by the array speaker 25-1 will be described.

[0054] Similar to the aforementioned sound leakage of the target sound into the area R11, the concealed sound A leaks to the right of the area R11 in the figure. This leaked sound can be heard in the area R14 adjacent to the right of the area R11.

[0055] In such a case, in area R14 adjacent to the right of area R11, the actual environmental sound heard in area R14 and the leaked concealed sound A will overlap. In this case, if the concealed sound A has similar characteristics to the actual environmental sound in area R14, the listener will have a hard time noticing the leaked concealed sound A.

[0056] The actual environmental sound heard in area R14 is not the sound emitted by the array speaker 25-1, but the sound emitted from one or more sound sources that actually exist around area R14. Here, the actual environmental sound heard in area R14 will also be referred to as environmental sound C.

[0057] Here, in order to make the concealment sound A and the actual environmental sound C in area R14 sound with similar characteristics, for example, the sound observed in area R14 can be recorded (collected) in advance, and the resulting sound (environmental sound C) can be emitted from array speaker 25-1 as the concealment sound A.

[0058] Although the above has been described with respect to sound leakage of the concealment sound A emitted toward the area R11, the same can be said for the concealment sound B emitted toward the area R13.

[0059] In other words, in the diagram of area R13, if the actual environmental sound in area R15 adjacent to the left side is collected in advance and the collected sound is emitted from array speaker 25-2 as concealment sound B, it becomes difficult to notice the sound leakage of concealment sound B in area R15.

[0060] In addition, the example described here is one in which the concealment sound is emitted in the horizontal direction of the region R12 from which the target sound is emitted, i.e., toward the regions R11 and R13 adjacent to both the left and right sides. However, the present invention is not limited to this, and the concealment sound may be emitted in the vertical direction of the region R12, i.e., toward adjacent regions above or below.

[0061] <Explanation of the regeneration process> Next, the reproduction process performed by the sound emission system 11 will be described with reference to the flowchart of FIG.

[0062] In step S11, the audio reproducer 21 outputs a pre-stored concealment sound signal to the audio amplifier 23.

[0063] Here, the concealment sound signal output from the audio player 21 may be an audio signal obtained by, for example, collecting environmental sound in advance in an area adjacent to the area from which the array speaker 25 emits sound, on the opposite side of the array speaker 26, or may be obtained by further performing equalization processing or the like on the audio signal.

[0064] The equalizing process here refers to a process of adjusting the magnitude of each frequency component of the concealment sound so that, for example, the frequency components that form peaks in the frequency waveform of the target sound are masked. Alternatively, the concealment sound signal may be an audio signal of the environmental sound, or a signal obtained by performing equalization on that audio signal, plus an audio signal of a sound that destroys the characteristics of the target sound.

[0065] Alternatively, the concealed sound signal may be an audio signal of environmental sound, or a signal that has been subjected to equalization processing to mask the target sound, and then further subjected to equalization processing that adds frequency characteristics that destroy the characteristics of the target sound.

[0066] In step S12, the audio player 22 outputs the target sound signal stored in advance to the audio amplifier 24.

[0067] In step S13, the audio amplifiers 23 and 24 amplify the concealment sound signal supplied from the audio reproducer 21 and the target sound signal supplied from the audio reproducer 22, and supply them to the array speakers 25 and 26.

[0068] In step S14, the array speaker 25 and the array speaker 26 output (emit) sounds based on the concealment sound signal and the target sound signal supplied from the audio amplifier 23 and the audio amplifier 24. As a result, the array speaker 25 reproduces the concealment sound, and the array speaker 26 reproduces the target sound.

[0069] When the concealment sound and the target sound are reproduced in this manner, the reproduction process ends.

[0070] In this way, the sound emission system 11 emits not only the target sound but also the concealment sound. In this way, it is possible to make it difficult to hear the sound leaking outside the designated direction.

[0071] For example, in the example described with reference to FIG. 2, by emitting concealment sound A and concealment sound B based on the concealment sound signal obtained by performing the above-described equalizing process, it is possible to make it difficult to perceive sound leakage of the target sound in areas R11 and R13 that are outside the specified direction of the target sound, i.e., in a direction different from the target direction.

[0072] Furthermore, by emitting concealment sound A and concealment sound B based on a concealment sound signal obtained from a signal obtained by actually picking up environmental sound, not only can sound leakage be made less perceptible in areas R14 and R15, but it can also be made to sound as if only actual environmental sound is being heard in areas R11 and R13.

[0073] Second Embodiment <Example of sound output system configuration> (Sound picked up by microphone and released as concealment sound) Furthermore, a sound output system to which the present technology is applied can also be configured, for example, as shown in Fig. 4. Note that in Fig. 4, parts corresponding to those in Fig. 1 are given the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0074] The sound output system 51 shown in Figure 4 has a microphone 61-1, a microphone 61-2, a microphone processing device 62-1, a microphone processing device 62-2, an audio player 22, an audio amplifier 23-1, an audio amplifier 23-2, an audio amplifier 24, an array speaker 25-1, an array speaker 25-2, and an array speaker 26.

[0075] The configuration of the sound emission system 51 shown in Figure 4 differs from the sound emission system 11 in that microphones 61-1 and 61-2 are newly provided, and microphone processing devices 62-1 and 62-2 are provided instead of the audio player 21, but in other respects it is the same as the configuration of the sound emission system 11.

[0076] The microphone 61-1 is placed on the right side of a listener looking at the array speaker 25-1 from the front, that is, at a predetermined distance away from the array speaker 25-1 on the opposite side to the array speaker 26.

[0077] The microphone 61-1 picks up ambient sound in real time when emitting the target sound, for example, and supplies the resulting ambient sound signal to the microphone processing device 62-1. Note that the pickup of ambient sound by the microphone 61-1 does not necessarily have to be performed in real time.

[0078] The microphone processing device 62-1 converts the environmental sound signal supplied from the microphone 61-1 from an analog signal to a digital signal by A / D (Analog / Digital) conversion, and supplies the resulting digital signal to the audio amplifier 23-1 as a concealment sound signal.

[0079] The audio amplifier 23-1 amplifies the concealment sound signal supplied from the microphone processing device 62-1, and drives the array speaker 25-1 to emit sound based on the amplified concealment sound signal.

[0080] Similarly, the microphone 61-2 is placed on the left side of a listener looking at the array speaker 25-2 from the front, that is, at a predetermined distance away from the array speaker 25-2 on the opposite side from the array speaker 26.

[0081] The microphone 61-2 picks up ambient sound in real time when emitting the target sound, and supplies the resulting ambient sound signal to the microphone processing device 62-2. Note that the pickup of ambient sound by the microphone 61-2 does not necessarily have to be performed in real time.

[0082] The microphone processing device 62-2 converts the environmental sound signal supplied from the microphone 61-2 from an analog signal to a digital signal by A / D conversion, and supplies the resulting digital signal to the audio amplifier 23-2 as a concealment sound signal.

[0083] The audio amplifier 23-2 amplifies the concealment sound signal supplied from the microphone processing device 62-2, and drives the array speaker 25-2 to emit sound based on the amplified concealment sound signal.

[0084] In the following, when there is no need to particularly distinguish between microphone 61-1 and microphone 61-2, they will also be simply referred to as microphone 61. In the following, when there is no need to particularly distinguish between microphone processing device 62-1 and microphone processing device 62-2, they will also be simply referred to as microphone processing device 62.

[0085] In the sound output system 51, as in the sound output system 11, the speakers constituting the array speaker 25 and the array speaker 26 are arranged in a straight line, i.e., at equal intervals in the horizontal direction. Therefore, in this example, 16 × 3 speakers are arranged at equal intervals.

[0086] Next, with reference to Fig. 5, we will explain sound leakage that occurs when line array speakers or the like are used as the array speakers 25 and 26. In Fig. 5, parts that correspond to those in Fig. 2 or 4 are given the same reference numerals, and their explanation will be omitted as appropriate.

[0087] In the example of Figure 5, array speaker 25-1 emits concealed sound A obtained by collecting environmental sound with microphone 61-1, and array speaker 25-2 emits concealed sound B obtained by collecting environmental sound with microphone 61-2.

[0088] Here, the microphone 61-1 and the microphone 61-2 are arranged in the areas R14 and R15, respectively, that is, in areas near the areas R11 and R13 where the concealed sounds are emitted.

[0089] Also, it is assumed that the array speaker 26 emits audio such as an explanation of the displayed advertisement, that is, a target sound.

[0090] Furthermore, as in the example of Figure 2, the area in which the concealed sound A emitted by the array speaker 25-1 is most audible is area R11, the area in which the target sound is most audible is area R12, and the area in which the concealed sound B emitted by the array speaker 25-2 is most audible is area R13.

[0091] As described above, the target sound emitted by the array speaker 26 leaks out in directions outside the specified direction, i.e., toward area R11 or area R13, near the boundary between area R11 and area R12, and near the boundary between area R12 and area R13.

[0092] The target sound leaking out in this way is heard overlapping with the concealment sound A emitted by the array speaker 25-1 in, for example, the region R11. When a listener hears these overlapping sounds, the influence of the concealment sound A makes it difficult for the listener to notice (perceive) the sound leakage of the target sound.

[0093] For example, auditory masking occurs due to the influence of overlapping concealing sound A, which is a characteristic of the human ear known as the auditory masking effect, making it difficult to notice sound leakage.

[0094] Furthermore, the auditory masking effect can be enhanced by analyzing the frequency of the target sound and equalizing the frequency of the concealment sound A so as to conceal (mask) the frequency peak based on the principle of auditory masking.

[0095] Furthermore, if the target sound is frequency-analyzed and a sound that destroys its characteristics is superimposed on the concealment sound A and emitted, the leaking target sound can be made unclear, making it difficult for the listener to notice the leaking target sound.

[0096] Note that, although the above has explained the relationship between the target sound emitted toward area R12 and the concealment sound A emitted toward area R11, the same can be said for the relationship between the target sound emitted toward area R12 and the concealment sound B emitted toward area R13.

[0097] Next, sound leakage of the concealment sound A emitted into the region R11 by the array speaker 25-1 will be described.

[0098] Similar to the aforementioned sound leakage of the target sound into the area R11, the concealed sound A leaks to the right of the area R11 in the figure. This leaked sound can be heard in the area R14 adjacent to the right of the area R11.

[0099] In such a case, in the area R14, the actual environmental sound C heard in the area R14 and the concealed sound A leaking out will overlap and be heard.

[0100] In this case, if the concealment sound A has characteristics similar to those of the actual environmental sound C in the area R14, the listener will be less likely to notice the sound leakage of the concealment sound A.

[0101] In this example, the concealed sound A is obtained by microphone 61-1 picking up the actual environmental sound C. Therefore, the concealed sound A heard by a listener in area R14 is observed in approximately the same location as the actual environmental sound that overlaps with the concealed sound A, making it difficult to notice sound leakage.

[0102] Although the above has been described with respect to sound leakage of the concealment sound A emitted toward the area R11, the same can be said for the concealment sound B emitted toward the area R13.

[0103] In the sound emission system 51 described above, the playback process described with reference to Figure 3 is basically performed, but in the process corresponding to step S11, a concealment sound signal obtained from an environmental sound signal obtained by collecting sound using the microphone 61 is output to the audio amplifier 23.

[0104] <Modification 1 of the Second Embodiment> <Example of sound output system configuration> (If there are multiple microphones) In addition, in the sound emission system 51 shown in Figure 4, an example has been described in which one microphone 61 is placed in an area adjacent to the area where the concealed sound is emitted by the array speaker 25, but this is not limited to this, and multiple microphones may be placed.

[0105] For example, in the example shown in Figure 5, microphone 61 is used to pick up actual environmental sounds in the locations (areas) from which concealed sounds A and B emitted from array speaker 25 leak out, and areas R14 and R15 from which sound leakage occurs are areas of a certain range.

[0106] Therefore, the actual environmental sounds heard in these areas R14 and R15 are not exactly the same depending on the listening position. Therefore, by collecting and mixing the environmental sounds at each of these positions (locations), it may be possible to obtain the average environmental sound across the entire area R14 or area R15 where sound leakage occurs as the concealed sound.

[0107] In such a case, the sound output system is configured, for example, as shown in Fig. 6. In Fig. 6, parts corresponding to those in Fig. 4 are given the same reference numerals, and their explanation will be omitted as appropriate.

[0108] The sound output system 91 shown in Figure 6 has microphones 101-1 to 101-6, microphone processing devices 62-1, 62-2, an audio player 22, audio amplifiers 23-1, 23-2, audio amplifiers 24, array speakers 25-1, 25-2, and array speakers 26.

[0109] The configuration of the sound output system 91 differs from the configuration of the sound output system 51 in that microphones 101-1 to 101-6 are provided instead of the microphone 61, but in other respects it has the same configuration as the sound output system 51.

[0110] The microphones 101-1 to 101-3 are arranged on the right side of a listener looking at the array speaker 25-1 from the front, that is, at positions spaced a predetermined distance away from the array speaker 25-1 on the opposite side of the array speaker 26.

[0111] The microphones 101-1 to 101-3 pick up ambient environmental sounds and supply the resulting environmental sound signals to the microphone processing device 62-1.

[0112] The microphone processing device 62-1 performs A / D conversion and mixing on the environmental sound signals supplied from the microphones 101-1 to 101-3 to generate a final concealment sound signal, which is supplied to the audio amplifier 23-1.

[0113] The microphones 101-4 to 101-6 are arranged on the left side of a listener looking at the array speaker 25-2 from the front, that is, at positions spaced a predetermined distance away from the array speaker 25-2 on the opposite side of the array speaker 26.

[0114] The microphones 101-4 to 101-6 pick up ambient environmental sounds and supply the resulting environmental sound signals to the microphone processing device 62-2.

[0115] The microphone processing device 62-2 performs A / D conversion and mixing on the environmental sound signals supplied from the microphones 101-4 to 101-6 to generate a final concealment sound signal, which is supplied to the audio amplifier 23-2.

[0116] In the following description, when there is no need to particularly distinguish between the microphones 101-1 to 101-6, they will also be simply referred to as microphones 101.

[0117] Here, Fig. 7 shows an example of the arrangement of microphones 101. In Fig. 7, parts corresponding to those in Fig. 5 are given the same reference numerals, and their explanation will be omitted as appropriate.

[0118] In the example shown in Fig. 7, the speakers constituting the array speaker 25 and the array speaker 26 are arranged in a straight line, i.e., at equal intervals in the horizontal direction, as in the case shown in Fig. 5. Therefore, in this example, 16 × 3 speakers are arranged at equal intervals.

[0119] Furthermore, within region R14, three microphones 101-1 to 101-3 are arranged at positions spaced apart from one another, and similarly, within region R15, three microphones 101-4 to 101-6 are arranged at positions spaced apart from one another.

[0120] For example, if actual environmental sounds are picked up by three microphones 101 placed at positions apart from each other within area R14 and the resulting environmental sound signals are mixed, it is possible to obtain a signal that conceals the average environmental noise that would be heard within area R14. The same can be said for area R15 as for area R14.

[0121] <Explanation of the regeneration process> Next, a description will be given of the operation of the sound emitting system 91. That is, the reproduction process performed by the sound emitting system 91 will be described below with reference to the flowchart of FIG.

[0122] When the playback process is started, each microphone 101 starts picking up the surrounding environmental sound, and supplies the resulting environmental sound signal to the microphone processing device 62 .

[0123] In particular, here, the environmental sound signals obtained by the microphones 101-1 to 101-3 are supplied to a microphone processing device 62-1, and the environmental sound signals obtained by the microphones 101-4 to 101-6 are supplied to a microphone processing device 62-2.

[0124] In step S41, the microphone processing device 62 performs A / D conversion on each environmental sound signal supplied from each microphone 101, thereby converting the analog signal into a digital signal.

[0125] In step S42, the microphone processing device 62 performs mixing, that is, addition processing, based on the A / D converted environmental sound signals to generate a concealment sound signal.

[0126] For example, in the microphone processing device 62-1, the environmental sound signals supplied from the microphones 101-1 to 101-3 and subjected to A / D conversion are added together to form one concealed sound signal.

[0127] When mixing environmental sound signals, a weight corresponding to the placement position of each microphone 101 may be used to weight and add the environmental sound signals obtained by sound collection by each microphone 101, i.e., mix them in a certain ratio, to generate a concealment sound signal.

[0128] In step S43, the microphone processing device 62 outputs the digital concealment sound signal obtained by mixing to the audio amplifier 23.

[0129] In step S44, the audio player 22 outputs the target sound signal stored in advance to the audio amplifier 24.

[0130] For example, a target sound signal, which is an audio signal of a target sound such as a pre-recorded explanation of an advertisement to be displayed, is recorded in the audio player 22. The audio player 22 outputs the digital target sound signal to the audio amplifier 24 in response to a playback start signal or a button operation (not shown).

[0131] In step S45, the audio amplifiers 23 and 24 amplify the concealment sound signal supplied from the microphone processing device 62 and the target sound signal supplied from the audio reproducer 22, and supply them to the array speakers 25 and 26.

[0132] In step S46, the array speaker 25 and the array speaker 26 output (emit) sounds based on the concealment sound signal and the target sound signal supplied from the audio amplifier 23 and the audio amplifier 24. As a result, the array speaker 25 reproduces the concealment sound, and the array speaker 26 reproduces the target sound.

[0133] When the concealment sound and the target sound are reproduced in this manner, the reproduction process ends.

[0134] In this way, the sound emission system 91 emits not only the target sound but also the concealed sound. In this way, it is possible to make it difficult to hear sounds leaking outside the specified direction. In particular, the sound emission system 91 can record averaged environmental noise by mixing environmental sound signals obtained by microphones 101 placed in multiple different positions, making it possible to make sound leakage less noticeable.

[0135] <Modification 2 of the Second Embodiment> <Example of sound output system configuration> (When selecting from multiple pre-stored concealment signals) Incidentally, in the sound emission system 51 shown in FIG. 4, the microphone processing device 62-1 and the microphone processing device 62-2 may store concealment sound signals of a plurality of different concealment sounds obtained by recording a plurality of environmental sounds in advance.

[0136] In this case, for example, the microphone processing device 62 selects, based on the environmental sound signal obtained by the microphone 61, one of a plurality of concealment sound signals stored in advance to be output to the audio amplifier 23.

[0137] For example, when the sound emission system 51 is installed in a passageway of a station, it is conceivable that the environmental sound at the location where the system is installed will change over time.

[0138] Specifically, for example, the characteristics of environmental sounds during rush hour in the morning and those during quiet hours in the afternoon (environmental noise) are different.

[0139] For this reason, it is possible to record (collect) multiple environmental sounds at different times and days of the week, i.e., at different collection times, in advance, and store the signals of these environmental sounds in each microphone processing device 62 as concealment sound signals.

[0140] At this time, frequency analysis is performed in advance on each concealment sound signal, and the resulting feature data is associated with the concealment sound signal and stored in the microphone processing device 62. This feature data may be any data that indicates frequency-related characteristics, such as the frequency characteristics of the concealment sound signal.

[0141] In this way, when a plurality of pre-recorded concealment sound signals are stored in association with feature data, the sound emission system 51 performs a reproduction process shown in Fig. 9. That is, the reproduction process performed by the sound emission system 51 will be described below with reference to the flowchart in Fig. 9.

[0142] When the playback process is started, each microphone 61 starts picking up the surrounding environmental sound, and supplies the resulting environmental sound signal to the microphone processing device 62 .

[0143] In step S71, the microphone processing device 62 performs A / D conversion on the environmental sound signal supplied from the microphone 61, thereby converting the analog signal into a digital signal.

[0144] In step S72, the microphone processing device 62 accumulates the environmental sound signals for a predetermined period of time obtained in step S71, and performs frequency analysis on the accumulated environmental sound signals to generate feature data.

[0145] In step S73, the microphone processing device 62 compares the feature data obtained in step S72 with a plurality of pieces of feature data stored in advance, and selects, from the plurality of pieces of feature data, the feature data that is closest to the feature data obtained in step S72. The microphone processing device 62 also selects the concealing sound signal associated with the feature data selected in this manner.

[0146] Here, the feature data that is closest to each other means, for example, that the difference between the feature data is smallest or that the distance between the feature data is shortest.

[0147] The concealment sound signal selected in this manner is the one that is closest (similar) to the actual environmental sound signal, that is, the one that has the most similar characteristics, among the concealment sound signals stored in advance.

[0148] In step S74, the microphone processing device 62 outputs to the audio amplifier 23 the concealment sound signal that is stored in association with the feature data selected in step S73.

[0149] Once the concealment sound signal is output in this manner, the processing of steps S75 to S77 is then carried out and the playback processing ends. However, since these processing steps are the same as the processing steps S44 to S46 in FIG. 8, their description will be omitted.

[0150] In this way, the sound emission system 51 selects, from among a plurality of concealment sound signals prepared in advance, one that is closest to the environmental sound signal obtained by actually picking up sound with the microphone 61, and emits the concealment sound based on the selected concealment sound signal.

[0151] By doing this, it is possible to emit not only the target sound but also the concealment sound, making it difficult to hear sounds leaking outside the specified direction. In particular, it is possible to emit concealment sounds with characteristics similar to actual environmental sounds, further improving the effect of making leaking sounds difficult to hear.

[0152] Furthermore, by emitting a concealing sound with characteristics similar to actual environmental sounds, it is possible to suppress the audio loop (howling) described below.

[0153] <Modification 3 of the Second Embodiment> <Howling Suppression> In the sound emission system 51 shown in FIG. 4, the surrounding environmental sound is picked up by the microphone 61, and the resulting environmental sound signal is A / D converted by the microphone processing device 62 to a digital concealment sound signal.

[0154] The concealment sound signal is then amplified by an audio amplifier 23 and supplied to an array speaker 25, from which the concealment sound is emitted.

[0155] At this time, depending on the position of the microphone 61, the concealed sound emitted from the array speaker 25 may be picked up again by the microphone 61. Similarly, the target sound emitted from the array speaker 26 may also be picked up by the microphone 61. This may result in an audio loop, and in some cases, a howling phenomenon may occur.

[0156] Therefore, in order to suppress such howling, the microphone 61 may be placed at a position away from the area of ​​the sound emitted with directionality from the array speaker 25, i.e., the area R11 or area R13 in Figure 5 described above.

[0157] Specifically, for example, when collecting sound using microphone 61, it is possible to place microphone 61 in a position where the components (sound pressure level) of the target sound and concealed sound contained in the environmental sound signal obtained by the collection are below a predetermined value (predetermined level).

[0158] Another method for suppressing audio loops (howling) is to use a directional microphone as microphone 61, thereby selectively preventing sounds emitted from array speaker 25 and array speaker 26 from being picked up by microphone 61.

[0159] For example, one such method is to orient the acutely directional microphone so that the microphone 61 does not pick up sounds coming from the direction of the concealed sound or the target sound.

[0160] That is, in this example, the microphone 61 may be placed so that the direction in which the microphone 61 has lower sound pickup sensitivity than other directions (null directivity direction) faces the direction from which the concealed sound or target sound comes.

[0161] Alternatively, for example, microphone beamforming technology may be used to orient the null directivity of the microphone 61 toward the array speaker 25, thereby preventing the microphone 61 from picking up the concealed sound or the target sound. In this case, the microphone processing device 62 performs beamforming on the environmental sound signal.

[0162] Furthermore, instead of using beamforming, the microphone processing device 62 may perform any filtering process or the like on the environmental sound signal to suppress audio loops (howling) to generate a concealment sound signal.

[0163] For example, in the microphone processing device 62, a delay process may be performed to delay the environmental sound signal obtained by the microphone 61 by a predetermined time, i.e., by adding a delay to the environmental sound signal to make it a concealing sound signal, thereby suppressing audio loops (howling).

[0164] Alternatively, the microphone processing device 62 may perform notch filtering on the frequency amplified by the audio loop on the environmental sound signal obtained by the microphone 61, and use the resulting signal as a concealment sound signal to suppress the audio loop (howling). This reduces the frequency components at which the audio loop occurs.

[0165] Furthermore, in the microphone processing device 62, gain correction is performed on the environmental sound signal obtained by the microphone 61 by applying a predetermined gain that attenuates the audio loop, and the resulting signal is used as a concealment sound signal, thereby suppressing the audio loop (howling).

[0166] It is also possible to combine a plurality of methods for suppressing the audio loop, such as the arrangement of the microphone 61 and the filter processing described above.

[0167] <Fourth Modification of the Second Embodiment> <Regarding frequency response correction> (Correcting the characteristics of the array speaker and microphone to make the concealed sound closer to the ambient sound) Furthermore, in the sound emission system 51 shown in FIG. 4, it has been explained that the surrounding environmental sound is picked up by the microphone 61, and the resulting environmental sound signal is A / D converted by the microphone processing device 62 to become a digital concealed sound signal.

[0168] The concealment sound signal is then amplified by an audio amplifier 23 and supplied to an array speaker 25, from which the concealment sound is emitted.

[0169] In the process of emitting such concealed sounds, sounds having frequency characteristics that depend on the characteristics of the microphone 61 and the array speaker 25 are emitted from the array speaker 25 .

[0170] For example, assume that the array speaker 25 has the frequency characteristic indicated by the arrow Q11 in Fig. 10. In Fig. 10, the horizontal axis represents frequency, and the vertical axis represents the level of each frequency component.

[0171] 10, the frequency characteristics are such that the mid-to-high range is boosted. When using the array speaker 25 having such frequency characteristics, an equalizing process may be performed using an audio equalizer to correct the frequency characteristics of the concealment sound signal so that the frequency characteristics of the array speaker 25 after correction become flat as shown by arrow Q12.

[0172] Also, for example, it is assumed that the microphone 61 has the frequency characteristic shown by the arrow Q21 in Fig. 11. In Fig. 11, the horizontal axis represents frequency, and the vertical axis represents the level of each frequency component.

[0173] In the example shown by arrow Q21 in Fig. 11, the frequency characteristics are such that the high frequencies are boosted. When using microphone 61 with such frequency characteristics, an equalization process may be performed on the environmental sound signal using an audio equalizer to correct the frequency characteristics so that the frequency characteristics of microphone 61 after correction become flat, as shown by arrow Q22. Such equalization process can be achieved, for example, by filtering using a single filter or a combination of multiple filters.

[0174] When sound collected by the microphone 61 is emitted as concealed sound from the array speaker 25, if the frequency characteristics of the microphone 61 and the array speaker 25 are flat, the characteristics of the concealed sound will become closer to the characteristics of the original environmental sound during the process from sound collection to sound emission.

[0175] Therefore, in the microphone processing device 62, an equalization process is performed using an audio equalizer to correct the frequency characteristics of the environmental sound signal, and the resulting signal is used as a concealment sound signal, making it possible to output a sound that is closer to the environmental sound as the concealment sound.

[0176] That is, for example, an audio equalizer can be used to perform equalization processing on the environmental sound signal obtained by microphone 61 so that the environmental sound signal has the flat characteristics shown by arrow Q22 in Figure 11, and the resulting signal can be used as a concealment sound signal.

[0177] Furthermore, an equalization process can be performed on the concealment sound signal by an audio equalizer so that the emitted concealment sound has the flat characteristics shown by arrow Q12 in Fig. 10. Alternatively, an equalization process can be performed on the environmental sound signal (concealment sound signal) to add only one of the frequency characteristics shown by arrow Q12 in Fig. 10 and the frequency characteristics shown by arrow Q22 in Fig. 11.

[0178] In this way, by using an audio equalizer to raise or suppress the levels of specific frequency bands, such as the mid-high and high ranges, to achieve a flat frequency response, it is possible to emit concealed sound that is closer to the original environmental sound.

[0179] Although the above description has been given of a method for correcting frequency characteristics using an audio equalizer, the present invention is not limited to this, and any other method may be used to correct frequency characteristics.

[0180] For example, the impulse response may be measured in advance, a filter with the inverse characteristics of the impulse response may be calculated, and the obtained filter may be used to perform filtering on the environmental sound signal or the concealed sound signal. This advance measurement of the impulse response may be performed for each of the microphone 61 and the speaker array 25, or may be performed for the entire system of the microphone 61 and the speaker array 25.

[0181] Therefore, for example, a filter process using a synthesis filter of a filter that adds the inverse characteristic of the frequency characteristic indicated by arrow Q11 in FIG. 10 and a filter that adds the inverse characteristic of the frequency characteristic indicated by arrow Q21 in FIG. 11 may be performed as an equalization process on the environmental sound signal, and the resulting signal may be used as a concealment sound signal.

[0182] Furthermore, for example, filtering using either a filter that adds the inverse of the frequency characteristics indicated by arrow Q11 in Figure 10 or a filter that adds the inverse of the frequency characteristics indicated by arrow Q21 in Figure 11 may be performed as equalizing processing on the environmental sound signal.

[0183] Furthermore, even when suppressing audio loops or making the concealment sound closer to environmental sounds as described above, the concealment sound may also have frequency characteristics that cancel out the characteristics of the target sound.

[0184] In such cases, the concealment sound signal may be subjected to an equalization process that adds frequency characteristics that cancel out the characteristics of the target sound, or an audio signal having frequency characteristics that cancel out the characteristics of the target sound may be added to the concealment sound signal to produce the final concealment sound signal.

[0185] Third Embodiment <Concealed sounds and target sounds> Furthermore, in the above, it has been explained that in the sound output system 11, the sound output system 51, and the sound output system 91, a total of three array speakers consisting of two array speakers 25 and one array speaker 26 are arranged in a row (linearly).

[0186] In particular, an example has been described in which one target sound is emitted from the array speaker 26 located in the center of the three array speakers, and concealment sounds are emitted from each of the array speakers 15 located to the left and right of that array speaker 26.

[0187] However, in a sound emission system to which the present technology is applied, the number of target sounds is not limited to one, and multiple target sounds may be emitted simultaneously.

[0188] Specifically, for example, if five array speakers are arranged in a row (linearly), when the array speakers are viewed from the front, concealment sound 1, target sound 1, concealment sound 2, target sound 2, and concealment sound 3 may be emitted in this order from the left array speaker to the right array speaker.

[0189] As described above, according to the present technology, even if a target sound is diffused even when a directional speaker is used, the diffusion (sound leakage) of the target sound and the concealment sound can be made less noticeable by emitting a concealment sound toward an area adjacent to the area where the target sound is emitted. In other words, it is possible to make it less audible the sound leaking outside the specified direction.

[0190] In particular, by using a microphone to pick up actual environmental sounds in the area from which the concealed sounds leak out and using them as concealed sounds, sounds leaking outside the designated direction can be made even less audible.

[0191] In addition, audio loops (howling) can be suppressed by selecting an appropriate signal from among multiple concealment sound signals and performing gain correction on the concealment sound signal. Furthermore, by correcting the frequency characteristics of the array speaker or microphone, the characteristics of the concealment sound can be made closer to the characteristics of the actual environmental sound.

[0192] <Example of computer configuration> The above-described series of processes can be executed by hardware or software. When the series of processes is executed by software, the programs constituting the software are installed on a computer. Here, the term "computer" includes computers built into dedicated hardware, and general-purpose personal computers, for example, that can execute various functions by installing various programs.

[0193] FIG. 12 is a block diagram showing an example of the hardware configuration of a computer that executes the above-described series of processes by a program.

[0194] In the computer, a CPU (Central Processing Unit) 501, a ROM (Read Only Memory) 502, and a RAM (Random Access Memory) 503 are interconnected by a bus 504.

[0195] An input / output interface 505 is further connected to the bus 504. An input unit 506, an output unit 507, a recording unit 508, a communication unit 509, and a drive 510 are connected to the input / output interface 505.

[0196] The input unit 506 includes a keyboard, a mouse, a microphone, an image sensor, etc. The output unit 507 includes a display, a speaker, etc. The recording unit 508 includes a hard disk, a non-volatile memory, etc. The communication unit 509 includes a network interface, etc. The drive 510 drives a removable recording medium 511 such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory.

[0197] In a computer configured as described above, the CPU 501 performs the above-described series of processes by, for example, loading a program recorded in the recording unit 508 into the RAM 503 via the input / output interface 505 and the bus 504 and executing it.

[0198] The program executed by the computer (CPU 501) can be provided by being recorded on a removable recording medium 511 such as a package medium, for example. The program can also be provided via a wired or wireless transmission medium such as a local area network, the Internet, or digital satellite broadcasting.

[0199] In a computer, a program can be installed in the recording unit 508 via the input / output interface 505 by inserting a removable recording medium 511 into the drive 510. The program can also be received by the communication unit 509 via a wired or wireless transmission medium and installed in the recording unit 508. Alternatively, the program can be installed in the ROM 502 or the recording unit 508 in advance.

[0200] The program executed by the computer may be a program that processes in chronological order according to the order described in this specification, or may be a program that processes in parallel or at the required timing, such as when called.

[0201] Furthermore, the embodiments of the present technology are not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the present technology.

[0202] For example, this technology can be configured as cloud computing, in which a single function is shared and processed collaboratively by multiple devices via a network.

[0203] Furthermore, each step described in the above flowchart can be executed by one device, or can be shared and executed by multiple devices.

[0204] Furthermore, when one step includes multiple processes, the multiple processes included in that one step can be executed by one device or can be shared and executed by multiple devices.

[0205] Furthermore, the present technology can also be configured as follows.

[0206] (1) one or more first speakers that emit a target sound; one or more second speakers arranged adjacent to the one or more first speakers and emitting directional concealment sound; A sound emission system comprising: (2) The one or more second speakers are arranged adjacent to each end of the one or more first speakers. The sound emission system according to (1). (3) The concealment sound has frequency characteristics that cancel out the characteristics of the target sound. A sound emission system according to (1) or (2). (4) The one or more second speakers emit the concealment sound based on a concealment sound signal obtained based on a signal of an environmental sound collected in the vicinity of an area where the concealment sound is emitted. A sound emission system according to any one of (1) to (3). (5) The system further includes a plurality of microphones for collecting the environmental sounds. (4) A sound emission system according to the present invention. (6) The concealment sound signal is generated by mixing signals obtained by collecting sounds with the plurality of microphones at a certain ratio. (5) A sound emission system according to (5). (7) The one or more second speakers emit the concealment sound based on the concealment sound signal selected from the plurality of concealment sound signals obtained based on the plurality of environmental sound signals previously collected by the microphone at different timings. A sound emission system according to (5) or (6). (8) The microphone has a directivity that suppresses the emitted target sound or the concealed sound. A sound emission system according to any one of (4) to (7). (9) The concealment sound signal is a signal obtained by applying delay processing to the environmental sound signal. A sound emission system according to any one of (4) to (6). (10) The concealment sound signal is a signal obtained by performing a filter process on the environmental sound signal to suppress an audio loop of the target sound or the concealment sound. A sound emission system according to any one of (4) to (6). (11) The concealment sound signal is a signal obtained by performing gain correction on the environmental sound signal to suppress an audio loop of the target sound or the concealment sound. A sound emission system according to any one of (4) to (6). (12) The plurality of microphones are arranged at positions where the level of the target sound or the concealed sound contained in the picked-up environmental sound is equal to or lower than a predetermined level. A sound emission system according to any one of (4) to (11). (13) The concealment sound signal is a signal obtained by performing equalization processing on the environmental sound signal to add frequency characteristics that cancel out the characteristics of the target sound. A sound emission system according to any one of (4) to (6). (14) The concealment sound signal is a signal obtained by adding a sound signal having frequency characteristics that cancel out the characteristics of the target sound to the environmental sound signal. A sound emission system according to any one of (4) to (6). (15) The concealment sound signal is a signal obtained by performing equalization processing on the environmental sound signal based on at least one of the frequency characteristics of the plurality of microphones measured in advance and the frequency characteristics of the one or more second speakers. A sound emission system according to any one of (4) to (6). [Explanation of symbols]

[0207] 11 sound emission system, 21-1, 21-2, 21 audio reproducer, 22 audio reproducer, 25-1, 25-2, 25 array speaker, 26 array speaker, 61-1, 61-2, 61 microphone, 62-1, 62-2, 62 microphone processing device, 101-1 to 101-6, 101 microphone

Claims

1. one or more first speakers that emit a target sound; One or more second speakers arranged adjacent to the one or more first speakers and emitting directional concealment sound; a plurality of microphones for collecting environmental sounds in the vicinity of an area where the concealed sound is emitted; Equipped with The one or more second speakers emit the concealment sound based on the concealment sound signal selected from among a plurality of concealment sound signals obtained based on a plurality of environmental sound signals previously collected by the microphone at different timings, based on the environmental sound signal collected by the microphone. Sound emission system.

2. The one or more second speakers are disposed adjacent to each end of the one or more first speakers. A sound emission system according to claim 1.

3. The concealment sound has a frequency characteristic that cancels the characteristic of the target sound. A sound emission system according to claim 1.

4. The microphone has a directivity that suppresses the emitted target sound or the concealed sound. A sound emission system according to claim 1.

5. The plurality of microphones are arranged at positions where the level of the target sound or the concealed sound contained in the picked-up environmental sound is equal to or lower than a predetermined level. A sound emission system according to claim 1.

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