Sound system

Abstract

Provided is a sound system for a user using a seat of an airplane, a car, or the like, which reproduces a sound that cannot be heard by a user around without using earphones, headphones. In the sound system, it is an integer of N is 1 or more, a sound system for a user using a seat of an airplane, including: a reproduction device including an nth reproduction section (n = 1,..., N), the reproduction device outputs an audio signal based on a reproduction object, that is, an (2n-1)th audio signal, and an audio signal opposite in phase to the (2n-1)th audio signal, that is, an (2n)th audio signal; and a speaker system including an nth speaker unit pair (n = 1,..., N) disposed near a head of the user using the seat, the nth speaker unit pair includes: a speaker unit emitting a sound based on the (2n-1)th audio signal (hereinafter, referred to as a positive speaker unit); and a speaker unit emitting a sound based on the (2n)th audio signal (hereinafter, referred to as a negative speaker unit).

Description

Technical Field

[0001] This invention relates to a sound reproduction technology that can be used in audio systems installed in seats such as airplanes and automobiles. Background Technology

[0002] Previously, users used earphones or headphone jacks to watch movies and listen to music on airplanes (see Non-Patent Document 1). This was because if speakers were used, the reproduced sound would disturb the surrounding area and cause inconvenience to other users.

[0003] Existing technical documents

[0004] Non-patent literature

[0005] Non-patent document 1: In-machine air conditioning system / JAL air conditioning system, [online], [Reiwa March 10, 2020], インターネット (In-flight casino / JAL First Class, [online], [Reiwa March 10, 2020], Internet)<URL: https: / / www.jal.co.jp / jp / ja / inter / service / first / entertainment / index.html> Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] However, wearing headphones or over-ear headphones can be cumbersome for users. Additionally, some users dislike wearing them, citing reasons such as messing up their hairstyle. Others dislike the pressure on their ears caused by wearing them. Furthermore, users sometimes experience auditory fatigue from wearing headphones or over-ear headphones for extended periods.

[0008] To eliminate the need for wearing headphones or headsets, wavefront synthesis technology was also considered to synthesize a virtual sound field. However, this would require a large-scale speaker array, which is impractical.

[0009] Therefore, the object of the present invention is to provide an audio system for users using seats in airplanes or cars that reproduces sounds that cannot be heard by surrounding users without the use of headphones or headsets.

[0010] Methods for solving problems

[0011] One aspect of the present invention is an audio system for a user utilizing an aircraft seat, where N is an integer greater than or equal to 1. The system includes: a reproduction device comprising an nth reproduction unit (n=1, ..., N) that outputs an audio signal based on a reproduced object, namely a 2n-1th audio signal, and an audio signal out of phase with the 2n-1th audio signal, namely a 2nth audio signal; and a loudspeaker system comprising an nth loudspeaker unit pair (n=1, ..., N) disposed near the head of the user utilizing the seat, the nth loudspeaker unit pair comprising: a loudspeaker unit emitting sound based on the 2n-1th audio signal (hereinafter referred to as a positive loudspeaker). The nth speaker unit (hereinafter referred to as the negative speaker unit) emits sound based on the 2nth audio signal. The direction of the nth speaker unit pair relative to the user is set as the nth user direction (n=1, ..., N). The sound emitted from the positive speaker unit of the nth speaker unit pair toward the nth user direction is out of phase with the sound emitted from the positive speaker unit of the nth speaker unit pair toward the opposite direction to the nth user direction. The sound emitted from the negative speaker unit of the nth speaker unit pair toward the nth user direction is out of phase with the sound emitted from the negative speaker unit of the nth speaker unit pair toward the opposite direction to the nth user direction.

[0012] One aspect of the present invention is an audio system for users utilizing aircraft seats, where N is an integer greater than or equal to 1. The system includes: a playback device comprising an nth playback unit (n = 1, ..., N) that outputs an audio signal (i.e., a 2n-1th audio signal) based on a playback object, and an audio signal (i.e., a 2nth audio signal) that is out of phase with the 2n-1th audio signal; and a band-domain segmentation device comprising an nth band-domain segmentation unit (n = 1, ..., N) that generates a high-frequency signal (i.e., a 2n-1th high-frequency signal) and a low-frequency signal (i.e., a 2n-1th low-frequency signal) from the 2n-1th audio signal, and generates a high-frequency signal (i.e., a 2n-1th low-frequency signal) from the 2nth audio signal. The 2n high-frequency signal and the low-frequency signal are the 2n low-frequency signal; and a speaker system including an nth speaker unit pair (n=1, ..., N) disposed near the head of a user using the seat, the nth speaker unit pair including: a speaker unit that emits sound based on the 2n-1 low-frequency signal (hereinafter referred to as a positive speaker unit); a high-frequency speaker attached to the positive speaker unit that emits sound based on the 2n-1 high-frequency signal; a speaker unit that emits sound based on the 2n low-frequency signal (hereinafter referred to as a negative speaker unit); and a high-frequency speaker attached to the negative speaker unit that emits sound based on the 2n high-frequency signal.

[0013] One aspect of the present invention is an audio system for users utilizing aircraft seats, where N is an integer greater than or equal to 1. The system includes: a reproduction device comprising an nth reproduction unit (n=1, ..., N) that outputs an audio signal based on a reproduced object, namely a 2n-1th audio signal, and an audio signal out of phase with the 2n-1th audio signal, namely a 2nth audio signal; and a band-domain segmentation device comprising an nth band-domain segmentation unit (n=1, ..., N) that generates a high-frequency signal (i.e., the 2n-1th high-frequency signal) and a low-frequency signal (i.e., the 2nth low-frequency signal) from the 2n-1th audio signal. The n-1 low-frequency signal is generated from the 2n-th audio signal, i.e., the 2n-th low-frequency signal; and the loudspeaker system includes an nth loudspeaker unit pair (n=1, ..., N) disposed near the head of the user using the seat, the nth loudspeaker unit pair including: a loudspeaker unit that emits sound based on the 2n-1 low-frequency signal (hereinafter referred to as the positive loudspeaker unit); a high-frequency loudspeaker that emits sound based on the 2n-1 high-frequency signal and is housed in a loudspeaker housing; and a loudspeaker unit that emits sound based on the 2n-th low-frequency signal (hereinafter referred to as the negative loudspeaker unit).

[0014] Invention Effects

[0015] According to the present invention, it is possible to reproduce sounds that can only be heard within an extremely limited and narrow range. Attached Figure Description

[0016] Figure 1 It is a diagram used to illustrate the directivity of sound emitted from a loudspeaker.

[0017] Figure 2 It is a diagram used to illustrate the directivity of sound emitted from a loudspeaker unit.

[0018] Figure 3 It is a diagram used to illustrate the sound emitted from the speaker unit.

[0019] Figure 4 It is a diagram used to illustrate the directivity of the sound emitted from the loudspeaker unit.

[0020] Figure 5 It is a diagram showing the experimental setup (the positional relationship between the speaker and the microphone).

[0021] Figure 6 It is a diagram showing the experimental setup (the positional relationship between the speaker unit and the microphone).

[0022] Figure 7 It is a diagram showing the experimental setup (the positional relationship between the speaker unit and the microphone).

[0023] Figure 8 It is a diagram showing the experimental setup (other measurement locations).

[0024] Figure 9 This is a graph representing the experimental results (condition 1).

[0025] Figure 10 This is a graph representing the experimental results (condition 2).

[0026] Figure 11 This is a graph representing the experimental results (condition 3).

[0027] Figure 12 This is a graph representing the experimental results (condition 4).

[0028] Figure 13 This diagram shows an example of an audio system installed in an airplane seat.

[0029] Figure 14 This is a block diagram illustrating an example of the structure of an audio system 100.

[0030] Figure 15 This is a block diagram illustrating an example of the configuration of the audio system 102.

[0031] Figure 16 This is a diagram showing an example of the structure of a speaker unit 122 with component 1222 installed.

[0032] Figure 17 This is a block diagram illustrating an example of the structure of the audio system 104.

[0033] Figure 18 This is a block diagram illustrating an example of the structure of an audio system 200.

[0034] Figure 19 This is a block diagram illustrating an example of the structure of an audio system 300.

[0035] Figure 20 This is a block diagram illustrating an example of the configuration of the audio system 106.

[0036] Figure 21 This is a diagram showing an example of the structure of a speaker unit 122 with component 1224 installed.

[0037] Figure 22 This is a block diagram illustrating an example of the structure of the audio system 108. Detailed Implementation

[0038] Hereinafter, embodiments of the present invention will be described in detail. Furthermore, components having the same function will be labeled with the same numbers, and repeated descriptions will be omitted.

[0039] <Technological Background>

[0040] First, the directivity of sound emitted from the loudspeaker will be explained. Next, the directivity of sound emitted from the loudspeaker unit of the present invention will be explained. Finally, the results of experiments confirming the effectiveness of the loudspeaker unit of the present invention will be explained.

[0041] 1: The Directivity of Sound Emitted from a Speaker

[0042] Typically, a loudspeaker consists of a loudspeaker unit and a loudspeaker enclosure. The loudspeaker unit is a component that includes a vibrating plate that converts an acoustic signal, which is an electrical signal, into vibrations in the air (i.e., generates sound waves). The loudspeaker enclosure is the component that houses the loudspeaker unit.

[0043] When an audio signal is input to a loudspeaker, the diaphragm of the loudspeaker unit vibrates, radiating sound waves in two directions. Here, the sound waves radiated to the outside of the loudspeaker enclosure (i.e., the front of the loudspeaker unit) are called positive sound waves, and the sound waves radiated to the inside of the loudspeaker enclosure (i.e., the back of the loudspeaker unit) are called negative sound waves. Negative sound waves are sound waves with a phase opposite to that of positive sound waves. Figure 1 This is a diagram used to illustrate the directivity of sound emitted from a loudspeaker. For example... Figure 1 As shown, positive sound waves radiate outwards from the speaker in all directions, while negative sound waves do not appear outside the speaker enclosure. As a result, the sound radiated from the speaker can be heard over a wide range.

[0044] 2: Directionality of sound emitted by the speaker unit

[0045] Here, we will first explain the directivity of the sound emitted from the speaker unit, which is a bare speaker. Figure 2 This diagram illustrates the directivity of sound emitted from a speaker unit. Unlike the case of a loudspeaker, in the case of a speaker unit alone, negative sound waves are radiated from the back of the speaker unit, which is concealed within the speaker enclosure. Therefore, as... Figure 2 As shown, the sound emitted from the speaker unit has a bidirectional characteristic.

[0046] In this invention, the bidirectionality is utilized. The following is a detailed description. First, as... Figure 3 In this way, two speaker units are arranged to create a speaker unit pair. When positive and negative acoustic signals are input to this speaker unit pair, the diaphragms of the two speaker units vibrate respectively, emitting sound based on these two acoustic signals. Thus, as... Figure 4As shown, sound is canceled omnidirectionally, except in the vicinity of the speaker unit pair. That is, sound is canceled only at locations sufficiently far from the speaker unit pair; sound is not canceled in the vicinity of the speaker unit pair. The reason sound is not canceled near the speaker unit pair is that the sound waves radiating from the front of the speaker unit in the vicinity of the speaker unit are out of phase with the sound waves that meander from the back.

[0047] In other words, when a specified audio signal is input into one speaker unit constituting a speaker unit pair and an audio signal with the opposite phase to the specified audio signal is input into the other speaker unit, by utilizing the property that the sound can only be heard in the vicinity of the speaker unit pair, it is possible to produce a situation where only users near the speaker unit pair can hear the sound, and other users cannot hear the sound.

[0048] 3: Experimental Results

[0049] Here, the results of the experiment measuring the frequency characteristics of a loudspeaker, a loudspeaker unit, and a loudspeaker unit pair are explained. In the experiment, a loudspeaker with a diaphragm having a diameter of 4.5 cm was used as the loudspeaker, loudspeaker unit, and loudspeaker unit pair (see reference). Figure 5 Remove the speaker enclosure from the speaker and use it only as a speaker unit (see reference). Figure 6 Place the two speaker units side by side (see reference) Figure 7 In addition, a microphone was set up under the following four conditions in order to measure the frequency characteristics of the loudspeaker, loudspeaker unit, and loudspeaker unit pair.

[0050] (Condition 1) 5cm from the front of the speaker

[0051] (Condition 2) 5cm from the front of the speaker unit

[0052] (Condition 3) 2cm from the front of the speaker unit

[0053] (Condition 4) 2cm from the front of the speaker unit pair

[0054] In addition, for comparison, microphones were placed at positions 100cm from the front, back, and sides of the speaker, speaker unit, and speaker unit pair under any conditions (see reference). Figure 8 ).

[0055] The experimental results are described below. Figure 9 , Figure 10 , Figure 11 , Figure 12The experimental results are shown in graphs illustrating the relationship between frequency and attenuation under conditions 1, 2, 3, and 4. Each graph shows four curves. The curve indicated by the arrow is formed by the sound from a microphone located 5cm or 2cm from the front. The other three curves are formed by microphones located 100cm from the front, back, and side. The curves at distances of 5cm or 2cm from the front are near the speaker, resulting in very high gain. Therefore, for easier observation, the curve at 5cm is plotted at -25dB using the three curves at 100cm. Similarly, the curve at 2cm is plotted at -32dB. Figure 9 and Figure 10 Comparison reveals that when using a loudspeaker, there is almost no difference among the four curves. However, when using a loudspeaker unit, there is a difference between the curve at a distance of 5cm from the front and the other three curves. This difference is more pronounced in the low-frequency range. Additionally, compared to... Figure 11 and Figure 12 As can be seen from the comparison, the curve at a position 2cm from the front of the speaker unit shows a greater difference than the other three curves.

[0056] Through the above experiments, it was confirmed that the sound emitted by the speaker unit pair of the present invention can only be heard in the vicinity of the speaker unit pair.

[0057] <First Implementation Method>

[0058] A system that reproduces an audio signal obtained from a reproduced object is called an audio system. An audio system includes a loudspeaker system to emit an audio signal as sound (hereinafter referred to as sound based on the audio signal). Here, the loudspeaker system is a device that converts an audio signal, which is an analog signal, into sound. Furthermore, the reproduced object is, for example, data recorded on CDs, DVDs, or recorders, data received via the Internet, or signals received via radio or television broadcasts—data or signals that can be processed to obtain an audio signal.

[0059] Here, an audio system is described that reproduces sound only for users located near the speaker system so that they can hear the sound based on an audio signal obtained from the reproduced object. That is, the reproduced sound of the audio system will not be heard by users other than those located near the speaker system. If such an audio system is used, for example, as an audio system for users using seats on an airplane, it is possible to provide a system in which only the user using that seat can hear the reproduced sound. Figure 13 This diagram shows an example of an audio system installed in an airplane seat. Figure 13The audio system is positioned on the seat so that it clips onto the user's head, with two speaker units positioned near the left and right ears. This audio system can also be installed in vehicles other than airplanes (cars, trains, etc.), reclining chairs, or even in wearable forms such as those worn on the shoulders. Alternatively, a pair of two driver units, equivalent to the aforementioned speaker unit pairs, can be installed in each unit of the headset or headphones. Headphones are generally classified into open-air and closed-back types; the application of this technology to open-air headphones, especially those with concerns about sound leakage, aims to reduce sound leakage.

[0060] The following is for reference Figure 14 Description of audio system 100. Figure 14 This is a block diagram representing the structure of the audio system 100. For example... Figure 14 As shown, the audio system 100 includes a playback device 110 and a loudspeaker system 120. The playback device 110 includes N playback units 112 (i.e., the first playback unit 112, ..., the Nth playback unit 112) (where N is an integer greater than or equal to 1). Furthermore, the loudspeaker system 120 includes N loudspeaker unit pairs 122 (i.e., the first loudspeaker unit pair 122, ..., the Nth loudspeaker unit pair 122). Each loudspeaker unit pair 122 includes two loudspeaker units (i.e., a positive loudspeaker unit 1221 and a negative loudspeaker unit 1221). An audio signal with an opposite phase to the audio signal input to the positive loudspeaker unit 1221 is input to the negative loudspeaker unit 1221. The loudspeaker system 120 is positioned close to the head of the user using the seat.

[0061] Furthermore, the direction opposite to the user in the nth speaker unit pair 122 is designated as the nth user direction (n=1, ..., N). The positive speaker unit 1221 and negative speaker unit 1221 of the nth speaker unit pair 122 (n=1, ..., N) are configured such that sound emitted from the positive speaker unit 1221 in the direction opposite to the nth user direction and sound emitted from the negative speaker unit 1221 in the direction opposite to the nth user direction are transmitted to the nth user direction through a detour. Here, the nth user direction refers to the frontal direction of the positive speaker unit 1221 and negative speaker unit 1221 of the nth speaker unit pair 122. Furthermore, the direction opposite to the nth user direction refers to the rearal direction of the positive speaker unit 1221 and negative speaker unit 1221 of the nth speaker unit pair 122.

[0062] Furthermore, the positive speaker unit 1221 and the negative speaker unit 1221 of the nth speaker unit group 122 (n=1, ..., N) are configured in a positional relationship that cancels each other out, so that the sound emitted from the positive speaker unit 1221 and the sound emitted from the negative speaker unit 1221 will not be heard by users using other seats.

[0063] The following is based on Figure 14 The operation of the audio system 100 will be explained.

[0064] The regeneration device 110 takes the sound signals obtained based on the regenerated object, namely the first sound signal, the third sound signal, ..., the (2N-1)th sound signal, as input, and outputs the first sound signal, the second sound signal, ..., the (2N)th sound signal. More specifically, the nth regeneration unit 112 (n=1,...,N) takes the (2n-1)th sound signal as input, generates the 2nth sound signal, which is an sound signal with the opposite phase to the (2n-1)th sound signal, and outputs the (2n-1)th sound signal and the 2nth sound signal. The (2n-1)th sound signal and the 2nth sound signal are respectively input to the positive speaker unit 1221 and the negative speaker unit 1221 of the nth speaker unit pair 122.

[0065] The loudspeaker system 120 takes the first audio signal, the second audio signal, ..., the 2Nth audio signal output from the regeneration device 110 as input, and emits sound based on the first audio signal, the second audio signal, ..., the 2Nth audio signal. More specifically, the nth loudspeaker unit pair 122 (n=1, ..., N) takes the 2n-1th audio signal and the 2nth audio signal as input, emitting sound based on the 2n-1th audio signal from the positive loudspeaker unit 1221, and emitting sound based on the 2nth audio signal from the negative loudspeaker unit 1221. Since the 2n-1th audio signal and the 2nth audio signal are in opposite phase, as explained in the <Background of the Technology>, the sound can only be heard near the seat where the loudspeaker system 120 is installed. For example, in the case of N=2, if the first audio signal and the third audio signal are respectively set as the right channel audio signal and the left channel audio signal of a certain sound source, stereo sound can only be heard near the seat where the loudspeaker system 120 is installed.

[0066] Furthermore, the sound emitted from the positive speaker unit 1221 of the nth speaker unit pair 122 towards the nth user and the sound emitted from the positive speaker unit 1221 of the nth speaker unit pair 122 in the opposite direction to the nth user are out of phase. Similarly, the sound emitted from the negative speaker unit 1221 of the nth speaker unit pair 122 towards the nth user and the sound emitted from the negative speaker unit 1221 of the nth speaker unit pair 122 in the opposite direction to the nth user are out of phase.

[0067] According to an embodiment of the invention, it is possible to reproduce sounds that can only be heard in an extremely limited and narrow range near the speaker system.

[0068] <Second Implementation Method>

[0069] The sound system 100 of the first embodiment has a narrow range in which the emitted sound can be heard, i.e., the so-called sweet spot. Here, a sound system with a structure that increases the sweet spot will be described.

[0070] The following is for reference Figure 15 Description of audio system 102. Figure 15 This is a block diagram showing the configuration of the audio system 102. For example... Figure 15 As shown, the audio system 102 includes a regeneration device 110 and a speaker system 120, just like the audio system 100. However, the audio system 102 differs from the audio system 100 in that it has a speaker unit pair 1222 mounting component 1222.

[0071] The following is based on Figure 15 The structure of the nth loudspeaker unit pair 122 (n=1,…,N) is described.

[0072] The nth loudspeaker unit pair 122 is equipped with a component 1222 that lengthens the path of sound emitted from the positive loudspeaker unit 1221 and the negative loudspeaker unit 1221 of the nth loudspeaker unit pair 122 in the direction opposite to the nth user direction as it detours towards the nth user direction (see reference). Figure 16 ). Component 1222 can be, for example, a partition plate that prevents sound from the back of the speaker unit from deflecting. This component 1222 is not for preventing sound deflection, but rather for increasing the phase difference between the sound deflecting from the back and the sound from the front, that is, a component installed to lengthen the path of the deflected sound.

[0073] The most effective point of the nth speaker unit pair 122 of the mounting component 1222 is larger than that of the nth speaker unit pair 122 in the first embodiment.

[0074] According to an embodiment of the invention, it is possible to reproduce sounds that can only be heard in an extremely limited and narrow range near the speaker system.

[0075] <Third Implementation Method>

[0076] Because high-frequency sounds have short wavelengths, it is difficult for sounds coming from behind and from the front to be in phase. Therefore, high-frequency sounds are more difficult to eliminate in the vicinity of the speaker unit and in relatively distant areas beyond the vicinity compared to low-frequency sounds. In the audio system 100 of the first embodiment, neither the positive speaker unit 1221 nor the negative speaker unit 1221 of the speaker unit pair 1222 are housed in a speaker enclosure. Therefore, according to the above-mentioned characteristics, high-frequency sounds can be heard over a wide range, sometimes resulting in sound leakage. Therefore, here, an audio system with a structure that prevents high-frequency sounds from leaking beyond the vicinity of the speaker system will be described.

[0077] The following is for reference Figure 17 Description of audio system 104. Figure 17 This is a block diagram showing the configuration of the audio system 104. For example... Figure 17 As shown, the audio system 104, like the audio system 100, includes a regeneration device 110 and a speaker system 120. However, the audio system 104 differs from the audio system 100 in that the positive speaker unit 1221 and the negative speaker unit 1221 of the speaker unit pair 122 are each equipped with a high-frequency speaker 1223. Here, the high-frequency speaker is a speaker unit used to regenerate high-frequency signals. In addition, the high-frequency speaker 1223 is not housed in a speaker enclosure, but is attached to the positive speaker unit 1221 and the negative speaker unit 1221 in a manner that does not leak sound from the rear.

[0078] The following is based on Figure 17 The operation of the loudspeaker system 120 will be explained.

[0079] The loudspeaker system 120 takes the first audio signal, the second audio signal, ..., the 2Nth audio signal output from the regeneration device 110 as input, and emits sound based on the first audio signal, the second audio signal, ..., the 2Nth audio signal. More specifically, the nth loudspeaker unit pair 122 (n=1, ..., N) takes the 2n-1th audio signal and the 2nth audio signal as input, and emits sound based on the 2n-1th audio signal from the positive loudspeaker unit 1221 and the high-frequency loudspeaker 1223 attached to the positive loudspeaker unit 1221, and emits sound based on the 2nth audio signal from the negative loudspeaker unit 1221 and the high-frequency loudspeaker 1223 attached to the negative loudspeaker unit 1221.

[0080] Although it has the property that the higher the frequency of the sound, the higher the linear propagation, the shape of the sound from the back of the high-frequency speaker 1223 does not leak, thus preventing the high-frequency sound emitted from the high-frequency speaker 1223 from leaking in all directions.

[0081] According to an embodiment of the invention, it is possible to reproduce sounds that can only be heard in an extremely limited and narrow range near the speaker system.

[0082] <Fourth Implementation Method>

[0083] A tweeter is a speaker unit used to reproduce high-frequency signals. Therefore, it is also possible to input only high-frequency signals to a tweeter through band-domain splitting. Therefore, an audio system that performs band-domain splitting will be described here.

[0084] The following is for reference Figure 18 Description of audio system 200. Figure 18 This is a block diagram representing the structure of the audio system 200. For example... Figure 18 As shown, the audio system 200 includes a playback device 110, a band splitting device 210, and a loudspeaker system 120. The band splitting device 210 includes N band splitting sections 212 (i.e., the first band splitting section 212, ..., the Nth band splitting section 212). The audio system 200 differs from the audio system 104 in that it includes the band splitting device 210.

[0085] The following is based on Figure 18 Explain the operation of the band segmentation device 210 and the loudspeaker system 120.

[0086] The frequency band division device 210 takes the first audio signal, the second audio signal, ..., the 2Nth audio signal output by the regeneration device 110 as input, and outputs the high-frequency signal (i.e., the first high-frequency signal and the low-frequency signal (i.e., the first low-frequency signal) of the first audio signal, the high-frequency signal (i.e., the second high-frequency signal and the low-frequency signal (i.e., the second low-frequency signal) of the second audio signal, ..., the high-frequency signal (i.e., the 2Nth high-frequency signal and the low-frequency signal (i.e., the 2Nth low-frequency signal) of the 2Nth audio signal. More specifically, the nth band division unit 212 (n=1, ..., N) takes the 2n-1th audio signal and the 2nth audio signal as input, generates the high-frequency signal (i.e., the 2n-1th high-frequency signal and the low-frequency signal (i.e., the 2n-1th low-frequency signal) of the 2nth audio signal, generates the high-frequency signal (i.e., the 2nth high-frequency signal and the low-frequency signal (i.e., the 2nth low-frequency signal) of the 2nth audio signal, and outputs the 2n-1th high-frequency signal, the 2nth low-frequency signal, the 2nth high-frequency signal, and the 2nth low-frequency signal.

[0087] The loudspeaker system 120 takes the first high-frequency signal, the first low-frequency signal, the second high-frequency signal, the second low-frequency signal, ..., the 2nth high-frequency signal, and the 2nth low-frequency signal output from the band division device 210 as inputs, and emits sound based on the first high-frequency signal, the first low-frequency signal, the second high-frequency signal, the second low-frequency signal, ..., the 2nth high-frequency signal, and the 2nth low-frequency signal. More specifically, the nth loudspeaker unit 122 (n=1, ..., N) takes the 2n-1th high-frequency signal, the 2n-1th low-frequency signal, the 2nth high-frequency signal, and the 2nth low-frequency signal as inputs, and emits sound based on the 2n-1th low-frequency signal and sound based on the 2n-1th high-frequency signal from the positive loudspeaker unit 1221 and the high-frequency loudspeaker 1223 attached to the positive loudspeaker unit 1221, respectively. It also emits sound based on the 2nth low-frequency signal and sound based on the 2nth high-frequency signal from the negative loudspeaker unit 1221 and the high-frequency loudspeaker 1223 attached to the negative loudspeaker unit 1221, respectively.

[0088] According to an embodiment of the invention, it is possible to reproduce sounds that can only be heard in an extremely limited and narrow range near the speaker system.

[0089] <Fifth Implementation Method>

[0090] In the audio system 200 of the fourth embodiment, the positive speaker unit 1221 and the negative speaker unit 1221 use speaker units attached to the high-frequency speaker 1223. Here, an audio system using a speaker unit pair including two speaker units and one high-frequency speaker will be described instead of using a speaker unit pair including speaker units attached to two high-frequency speakers.

[0091] The following is for reference Figure 19 Description of audio system 300. Figure 19 This is a block diagram representing the structure of the audio system 300. For example... Figure 19 As shown, the audio system 300 includes a regeneration device 110, a band splitting device 310, and a loudspeaker system 320. The band splitting device 310 includes N band splitting sections 312 (i.e., first band splitting section 312, ..., Nth band splitting section 312). Furthermore, the loudspeaker system 320 includes N loudspeaker unit pairs 322 (i.e., first loudspeaker unit pair 322, ..., Nth loudspeaker unit pair 322). Each loudspeaker unit pair 322 includes two loudspeaker units (i.e., positive loudspeaker unit 1221 and negative loudspeaker unit 1221) and a tweeter 3221. The audio system 300 differs from the audio system 200 in that it includes the band splitting device 310 and the loudspeaker system 320 instead of the band splitting device 210 and the loudspeaker system 120.

[0092] The preferred high-frequency loudspeaker 3221 is housed in the loudspeaker enclosure in a manner that prevents sound leakage from the rear. Additionally, the loudspeaker system 320 is positioned close to the head of the user using the seat.

[0093] Furthermore, the nth speaker unit pair 322 has its direction relative to the user designated as the nth user direction (n=1, ..., N). The positive speaker unit 1221 and negative speaker unit 1221 of the nth speaker unit pair 322 (n=1, ..., N) are configured such that sound emitted from the positive speaker unit 1221 in the direction opposite to the nth user direction and sound emitted from the negative speaker unit 1221 in the direction opposite to the nth user direction are transmitted to the nth user direction through a detour. Here, the nth user direction refers to the frontal direction of the positive speaker unit 1221, negative speaker unit 1221, and high-frequency speaker 3221 of the nth speaker unit pair 322. Furthermore, the direction opposite to the nth user direction refers to the rearal direction of the positive speaker unit 1221, negative speaker unit 1221, and high-frequency speaker 3221 of the nth speaker unit pair 322.

[0094] Furthermore, the positive speaker unit 1221 and negative speaker unit 1221 of the nth speaker unit group 322 (n=1, ..., N) are configured in a positional relationship that cancels each other out, so that the sound emitted from the positive speaker unit 1221 and the sound emitted from the negative speaker unit 1221 will not be heard by users using other seats.

[0095] The following is based on Figure 19 Explain the operation of the band segmentation device 310 and the loudspeaker system 320.

[0096] The band division device 310 takes the first audio signal, the second audio signal, ..., the 2Nth audio signal output from the regeneration device 110 as input, and outputs the high-frequency signal (i.e., the first high-frequency signal) and the low-frequency signal (i.e., the first low-frequency signal) of the first audio signal, the low-frequency signal (i.e., the second low-frequency signal) of the second audio signal, ..., the high-frequency signal (i.e., the 2N-1)th audio signal and the low-frequency signal (i.e., the 2N-1)th audio signal, ...

[0097] The loudspeaker system 320 takes the first high-frequency signal, the first low-frequency signal, the second low-frequency signal, ..., the (2n-1)th high-frequency signal, the (2n-1)th low-frequency signal, and the 2nth low-frequency signal output from the band division device 310 as input, and emits sound based on the first high-frequency signal, the first low-frequency signal, the second low-frequency signal, ..., the (2n-1)th high-frequency signal, the (2n-1)th low-frequency signal, and the 2nth low-frequency signal. More specifically, the nth loudspeaker unit 322 (n=1, ..., N) takes the (2n-1)th high-frequency signal, the (2n-1)th low-frequency signal, and the 2nth low-frequency signal as input, and emits sound based on the (2n-1)th high-frequency signal from the high-frequency loudspeaker 3221, emits sound based on the (2n-1)th low-frequency signal from the positive loudspeaker unit 1221, and emits sound based on the 2nth low-frequency signal from the negative loudspeaker unit 1221.

[0098] According to an embodiment of the invention, it is possible to reproduce sounds that can only be heard in an extremely limited and narrow range near the speaker system.

[0099] <Sixth Implementation Method>

[0100] The audio system 104 of the third embodiment becomes a system in which high-frequency sound is not easily leaked by using the speaker unit 1221 attached to the high-frequency speaker 1223. Here, an audio system in which high-frequency sound is not easily leaked by using a component with sound-absorbing properties instead of the speaker unit attached to the high-frequency speaker will be described.

[0101] The following is for reference Figure 20 Description of audio system 106. Figure 20 This is a block diagram showing the configuration of the audio system 106. For example... Figure 20 As shown, the audio system 106, like the audio system 104, includes a regeneration device 110 and a speaker system 120. However, the audio system 106 differs from the audio system 104 in that it uses a speaker unit 1221 not attached to the high-frequency speaker 1223 instead of the speaker unit 1221 attached to the high-frequency speaker 1223, and in that it uses a speaker unit mounting component 1224 for the speaker unit pair 122.

[0102] The following is based on Figure 20 The structure of the nth loudspeaker unit pair 122 (n=1,…,N) is described.

[0103] The nth speaker unit pair 122 is equipped with a component 1224 for absorbing sound emitted from the positive speaker unit 1221 and the negative speaker unit 1221 of the nth speaker unit pair 122 in the direction opposite to the direction of the nth user. Figure 21Component 1224 can be any component that can prevent high-frequency sound from being emitted from the rear. Alternatively, instead of placing component 1224 only on the rear of the speaker unit pair 122, component 1224 can be placed in a manner that surrounds the front of the speaker unit pair 122.

[0104] According to an embodiment of the invention, it is possible to reproduce sounds that can only be heard in an extremely limited and narrow range near the speaker system.

[0105] <Seventh Implementation Method>

[0106] The audio system 106 of the sixth embodiment becomes a system in which high-frequency sound is difficult to leak by using the speaker unit 1221 of the mounting member 1224. Here, the audio system is described as follows: instead of using a pair of speaker units with sound-absorbing material, by accommodating the speaker units of the speaker unit pair in an open speaker enclosure, it is difficult to capture high-frequency sound.

[0107] The following is for reference Figure 22 Description of audio system 108. Figure 22 This is a block diagram showing the configuration of the audio system 108. For example... Figure 22 As shown, the audio system 108, like the audio system 106, includes a regeneration device 110 and a speaker system 120. The audio system 108 differs from the audio system 106 in that it includes a speaker unit pair 122, which includes a speaker unit 1221 housed in a speaker enclosure 1225, in place of the speaker unit pair 122 of the mounting member 1224.

[0108] The following is in accordance with Figure 22 The structure of the nth loudspeaker unit pair 122 (n=1,…,N) is described.

[0109] The positive speaker unit 1221 and the negative speaker unit 1221 of the nth speaker unit pair 122 are respectively housed in the speaker enclosure 1225. In addition, the speaker enclosure 1225 has a plurality of holes.

[0110] According to an embodiment of the invention, it is possible to reproduce sounds that can only be heard in an extremely limited and narrow range near the speaker system.

[0111] Postscript

[0112] The above description of embodiments of the present invention is for illustrative and descriptive purposes only. It is not intended to be exhaustive, nor is it intended to limit the invention to its strict form. Variations and modifications may be made based on the above teachings. The embodiments are chosen to provide the best illustration of the principles of the invention, and various embodiments or modifications will be employed by those skilled in the art to suit familiar practical use. All such variations and modifications are within the scope of the invention as determined by the appended claims, interpreted in accordance with the width impartially, legally, and fairly granted.

Claims

1. A sound system, characterized in that, include: The playback device includes an nth playback unit that outputs an acoustic signal obtained based on the playback object, namely the (2n-1)th acoustic signal, and an acoustic signal that is out of phase with the (2n-1)th acoustic signal, namely the 2nth acoustic signal, where n = 1, ..., N, and N is an integer greater than or equal to 1; and A loudspeaker system includes an nth pair of loudspeaker units positioned near the user's head. This nth pair of loudspeaker units includes: a positive loudspeaker unit that emits sound based on a 2n-1th acoustic signal; and a negative loudspeaker unit that emits sound based on a 2nth acoustic signal. In this context, the direction of the nth speaker unit relative to the user is defined as the nth user direction. The sound emitted from the positive speaker unit of the nth speaker unit pair towards the nth user is out of phase with the sound emitted from the positive speaker unit of the nth speaker unit pair in the opposite direction to the nth user. The sound emitted from the negative speaker unit of the nth speaker unit pair towards the nth user and the sound emitted from the negative speaker unit of the nth speaker unit pair in the opposite direction to the nth user are out of phase. The positive and negative speaker units of the nth speaker unit pair are configured such that sound emitted from the positive speaker unit in the direction opposite to the nth user and sound emitted from the negative speaker unit in the direction opposite to the nth user are transmitted towards the nth user through a detour. A component is installed in the nth speaker unit pair to absorb high-frequency sounds emitted from the positive and negative speaker units of the nth speaker unit pair in the direction opposite to the nth user's direction. The user can hear the sound only in the region where the phase of the sound waves emitted by each speaker unit in the nth speaker unit pair toward the nth user is inconsistent with the phase of the sound waves that meander from each speaker unit in the opposite direction to the nth user.

2. The audio system according to claim 1, characterized in that, The sound emitted from the positive speaker unit of the nth speaker unit pair towards the nth user is out of phase with the sound emitted from the negative speaker unit of the nth speaker unit pair towards the nth user.

3. The audio system according to claim 2, characterized in that, The following component is installed in the nth speaker unit pair to lengthen the path of the sound emitted from the positive and negative speaker units of the nth speaker unit pair in the direction opposite to that of the nth user, so that the sound detours towards the nth user.

4. The audio system according to any one of claims 1 to 3, characterized in that, The positive and negative speaker units of the nth speaker unit pair are configured in a mutually exclusive positional relationship so that the sound emitted from the positive speaker unit and the sound emitted from the negative speaker unit cannot be heard by users other than the user.

Images