JP2688051B2 - Broadcast space limiting device - Google Patents

Broadcast space limiting device

Info

Publication number
JP2688051B2
JP2688051B2 JP62071125A JP7112587A JP2688051B2 JP 2688051 B2 JP2688051 B2 JP 2688051B2 JP 62071125 A JP62071125 A JP 62071125A JP 7112587 A JP7112587 A JP 7112587A JP 2688051 B2 JP2688051 B2 JP 2688051B2
Authority
JP
Japan
Prior art keywords
wave
carrier
speaker
coswt
space
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
JP62071125A
Other languages
Japanese (ja)
Other versions
JPS63236500A (en
Inventor
正之 常盤
洋介 後神
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Takenaka Corp
Original Assignee
Takenaka Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Takenaka Corp filed Critical Takenaka Corp
Priority to JP62071125A priority Critical patent/JP2688051B2/en
Publication of JPS63236500A publication Critical patent/JPS63236500A/en
Application granted granted Critical
Publication of JP2688051B2 publication Critical patent/JP2688051B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Landscapes

  • Circuit For Audible Band Transducer (AREA)

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明は放送空間の限定装置に係り、特に音声を任意
の空間に限定する放送空間の限定装置に関する。 〔従来の技術〕 従来より、音はスピーカ等から発せられ空間に広く伝
播するため必要場所以外に伝わり、色々な場所で音を同
時に発生するとお互いに干渉し合ったりして混乱を生じ
る。従って、街角に見る大型デイスプレイ等も交通上の
障害あるいは騒音となるため大規模なものは無声が多
い。一方、壁などによらずに音を任意空間に限定するた
めにはスピーカの特性(指向性)や配置により限定して
いた。 〔発明が解決しようとする問題点〕 しかしながら、スピーカの指向性に対してある程度指
向の強いものはできても音の到達距離を制御する事は出
力に頼ることしかなく、完全には音を任意空間に限定す
ることはできない、という問題点がある。 本発明は上記問題点を解決すべく成されたもので、音
を任意の空間に限定することができる放送空間の限定処
理を提供することを目的とする。 〔問題点を解決するための手段〕 上記目的を達成するため、本発明は、通話者のみが存
在する開放された任意の空間内の特定の可聴領域にのみ
音声を限定する放送空間の限定装置であって、2つの超
高周波の搬送波を同期させて発生可能な搬送発生手段
と、前記搬送波発生手段によって発生された搬送波の一
方を用いて、入力される音声信号を変調する変調手段
と、前記変調手段によって変調された変調波を平面波と
して出力する第1のスピーカと、前記第1のスピーカか
ら前記搬送波の波長の整数倍の間隔をあけて対面して配
置され、前記搬送波発生手段により発生された搬送波の
他方を平面波として出力する第2のスピーカと、を有す
ることを特徴とする。 〔作用〕 本発明の放送空間の限定装置では、搬送波発生手段に
よって発生された超高周波の搬送波の一方を用いて、変
調手段へ入力される音声信号が変調されて変調波とされ
る。この変調波は第1のスピーカから平面波として出力
される。一方、搬送波発生手段により発生された超高周
波の搬送波の他方が、第2のスピーカから平面波として
出力される。これらの平面波は超高周波であるため、そ
れぞれ単独では直接人間が聞き取ることはできないが、
搬送波の波長の整数倍の間隔をあけて対面配置された第
1と第2のスピーカの間の空間では、振幅の異なる平面
波同士が干渉し、音声信号が生じる。このため、この開
放された空間に存在する通話者のみが、この音声信号を
識別できる。 また、干渉面上の各点によってスピーカからの伝送時
間に差が生じるということがなく、各点において伝送時
間が等しくなり、干渉点は、平面の全体で時間的なずれ
を生じることなく一様に分布する。これにより、一度
に、平面全体にわたる広い可聴領域を得ることができ
る。また、平面波が干渉する平面の近傍以外の場所で
は、平面波の位相のずれが大きくなるため平面波同士が
干渉せず、音声信号が生じない。このため、例えば、通
話者のみ存在する任意の開放された空間において、広い
可聴領域を確保すると共に、この可聴領域以外の空間に
音が漏れないようにすることができる。 〔実施例〕 以下本発明の放送空間の限定装置が電話システムに適
用された実施例を詳細に説明する。 第1図に示されるように、音声信号v(t)が平衡変
調器10に入力されると、平衡変調器10によって音声信号
v(t)が搬送波発生器12によって生成された搬送波co
swtで変調される。 この搬送波coswtの帯域は、人間の耳に聞こえる可聴
波帯域と周波数が可聴波以下の超低周波帯域と周波数が
可聴波以上の超高周波帯域とに分類することができる
が、可聴波では、人間の耳に聞こえてしまうため雑音と
なってしまう。超低周波では、人体に対して頭痛、吐き
気等の悪影響がある。また、搬送波成分caswtを持つ変
調波を非線形特性を利用して復調すると一般に非線形特
性は入力xに対して(1)式のように表わされる。 y=a0+a1x+a2x2+a3x3+・・・・・ ……(1) ここに搬送波成分coswtを持つ信号が入力すると出力
して(2)式のようにcos2wt、cos3wt、・・・の項が現
われ、2次以上の項は周波数2wt、3wt、・・・の高周波
を生みだす。 一般の復調回路では高周波成分をフイルタによってカ
ツトすることができる。また、搬送波が超高周波であれ
ば高調波成分はさらに周波数の高い超音波(不可聴)と
なり問題にならない。 また、搬送波が超低周波であれば可聴周波数を持つ高
調波が雑音となって現われてくる。従って、搬送波の帯
域は超高周波を使用する。また、この超高周波は空気中
伝播の際の減衰が大きいため反射の減衰が大きく反射波
の影響を抑えることができる。 一方超高周波の搬送波Acoswtで音声信号v(t)を平
衡変調器10によって振幅変調(AM)すると(3)式の形
に変調される。 f1(t)=A0{1+kv(t)}coswt ……(3) これを非線形特性の(1)式に代入すると、 (4)式のようになり、音声信号v(t)に比例した成
分(a2A0 2kv(t))が表われ、超音波変調による暗号
化の役を成さない。そこで、平衡変調器10によって一般
の振幅変調波 f1(t)=A0{1+kv(t)}coswt ……(3) の位相を逆にした変調波の差 f2(t)=A0{1−kv(t)}coswt ……(5) をとった搬送波抑圧変調にすると、搬送波抑圧変調波は
(6)式のようになる。 f(t)=f1(t)−f2(t) =2A0kv(t)coswt =k0v(t)coswt ……(6) (ただし、k0=2A0k) この抑圧変調波k0v(t)coswtを(1)式の非線形特
性に入力すると、(7)式のようになり音声信号v
(t)の成分は出てこないので音声信号v(t)を平衡
変調器10によって搬送抑圧変調方式での変調にする。 従って、第1図に示されるように平衡変調器10より抑
圧変調波k0v(t)coswtがスピーカ14より出力される一
方搬送波発生器12により、平衡変調器10に出力する搬送
波coswtと同期させながら搬送波coswtがスピーカ16より
出力される。すると、抑圧変調波k0v(t)coswtと搬送
波coswtとが干渉され、その干渉点において(8)式の
ように合成波{1+k0v(t)}coswtを得る。 k0v(t)coswt+coswt={1+k0v(t)}coswt ……
(8) ここでこの合成波{1+k0v(t)}coswtは空間にい
る通話者18の耳の非線形特性に入力されて(9)式を得
る。 ここで第5項以降は搬送波およびその高調波成分であ
る超音波なので人間の耳には不可聴である。また、第1
項および第2項は直流分であり、不可聴である。よって
通話者18の耳に復調信号としてとらえるのは である。ここで第2項は復調ひずみであり雑音となって
しまうがk0の値を調整することによって影響を小さくす
ることができる。 また、スピーカ14、16との距離を抑圧変調波k0v
(t)coswtと搬送波coswtとの位相がずれないように波
長の整数倍に設定しなければならない。また、それぞれ
のスピーカ14、16から出力される抑圧変調波k0v(t)c
oswtと搬送波coswtとの干渉点は平面上に分布するよう
にしなければならない。 第2図に示されるように一般にある音源20、22から発
せられた音波は球面波となって伝送されていくが、それ
では干渉面上の各ポイントA、B、Cの伝送時間をTA
TB、TCとすると伝送時間はTA<TB<TCとなり伝送遅延が
発生してしまう。従って、第3図に示されるように各ポ
イントA、B、Cの伝送時間がTA=TB=TCとなる平面波
を発生するスピーカを使用して干渉点を平面上に分布す
る。 一方、搬送波に周期関数coswtを使用しているために
干渉面は2つのスピーカ14、16の中点ではなく、搬送波
の波長間隔で存在する(干渉じま現象)。従って、それ
ぞれの干渉面は時間的なずれを持っているので、左右の
耳が別々の干渉面に位置すると左右の耳に聞こえる音声
は時間的なずれを待つことになり耳の間隔を17cmとして
時間的なずれは(11)式より5×10-4secとなる。 しかしながら、干渉面の間隔が非常に短くなり時間的
なずれも無視できるとして干渉面の重なりを1つのエリ
アとしてとらえることができる。 また、複数の干渉面は第4図乃至第6図に示されるよ
うにスピーカ14、16の設置方向(上下、前後、左右)に
よってそれぞれ異なった方向に重なることになる。 スピーカ14、16を第4図に示すように通話者18の上下
に設置した場合には、干渉面は水平に重なり、左右の耳
が同一干渉面上になるので、平面上の移動ができる。し
かしながら、下方からの音波に対するイス、自分の体な
どの障害物が多くなってしまう。 また、スピーカ14、16を第5図に示すように通話者18
の左右に設置した場合には、干渉面は体の側面に平行に
なるので、左右の耳は違う干渉面上になる。また、音波
に対して自分の頭が障害物となってしまう。 また、スピーカ14、16を第6図に示すように通話者18
の前後に設置した場合には、干渉面は体の正面に平行に
なり、左右の耳が同一干渉面上になるので、自分の体が
音波の障害にはなりにくい。 以上の事から、スピーカ14、16を通話者18の前後に設
置することが好ましい。 以上説明したように電話システムに本発明の放送空間
の限定装置を適用したことにより、音声信号を不可聴波
である超音波にて変調し、通話者のいるある特定のエリ
アでのみ復調することができるので、受話器あるいはヘ
ツドホンなどの装置を必要とせず無線化、無装置化がで
きる。また、不可聴波による変調によりスピーカホンな
どのように電話の秘話性が無くなったり、通話者以外の
人間に聞こえて雑音、騒音となることがなく無音化(無
騒音、秘話性)が計れる。 〔発明の効果〕 以上説明したように本発明によれば、変調波と搬送波
とが干渉された空間に入った人のみが音声として識別す
ることができるので、当該空間以外の人には音が聞こえ
ない。従って、音を任意の空間に限定することができ
る、という効果が得られる。 また、変調波と搬送波はそれぞれ平面波として出力さ
れるので、干渉点が平面上に分布し、この平面上では伝
送遅延が生じない。
The present invention relates to a broadcast space limiting device, and more particularly to a broadcast space limiting device for limiting audio to an arbitrary space. [Prior Art] Conventionally, sound is emitted from a speaker or the like and widely propagates in a space, so that the sound is transmitted to a place other than a necessary place. When sounds are simultaneously generated in various places, they interfere with each other and cause confusion. Therefore, a large-scale display seen on a street corner also causes a traffic obstacle or noise, so that a large-scale display is often silent. On the other hand, in order to limit the sound to an arbitrary space without depending on the wall or the like, it is limited by the characteristics (directivity) and the arrangement of the speakers. [Problems to be Solved by the Invention] However, even if a speaker having a strong directivity to some degree of directivity can be formed, controlling the sound reaching distance depends only on the output, and the sound is completely arbitrary. There is a problem that it cannot be limited to space. The present invention has been made to solve the above problems, and an object of the present invention is to provide a broadcast space limiting process capable of limiting sound to an arbitrary space. [Means for Solving Problems] In order to achieve the above object, the present invention provides a broadcast space limiting device that limits audio only to a specific audible area in an open arbitrary space where only a caller exists. A carrier generating means capable of generating two super-high frequency carrier waves in synchronization with each other; a modulating means for modulating an input audio signal using one of the carrier waves generated by the carrier wave generating means; The first speaker that outputs the modulated wave modulated by the modulating means as a plane wave is arranged to face the first speaker with an interval that is an integer multiple of the wavelength of the carrier wave, and is generated by the carrier wave generating means. And a second speaker that outputs the other of the carrier waves as a plane wave. [Operation] In the broadcast space limiting device of the present invention, the audio signal input to the modulating means is modulated into a modulated wave by using one of the super-high frequency carrier waves generated by the carrier wave generating means. This modulated wave is output as a plane wave from the first speaker. On the other hand, the other of the super-high frequency carrier waves generated by the carrier wave generating means is output as a plane wave from the second speaker. Since these plane waves are super high frequencies, they cannot be heard directly by humans,
In the space between the first and second loudspeakers facing each other with an interval that is an integral multiple of the wavelength of the carrier wave, plane waves having different amplitudes interfere with each other to generate a voice signal. Therefore, only the caller existing in this open space can identify this voice signal. Also, there is no difference in the transmission time from the speaker depending on each point on the interference surface, the transmission time is equal at each point, and the interference points are uniform over the entire plane without any time lag. Distributed in. As a result, a wide audible area over the entire plane can be obtained at one time. In addition, in a place other than the vicinity of the plane where the plane waves interfere with each other, the phase shift of the plane waves becomes large, so that the plane waves do not interfere with each other and no audio signal is generated. Therefore, for example, it is possible to secure a wide audible area in any open space where only the caller exists, and prevent sound from leaking into a space other than this audible area. [Embodiment] An embodiment in which the broadcast space limiting apparatus of the present invention is applied to a telephone system will be described in detail below. As shown in FIG. 1, when the voice signal v (t) is input to the balanced modulator 10, the balanced modulator 10 generates the voice signal v (t) by the carrier wave generator 12 to generate a carrier wave co.
Modulated by swt. The band of this carrier wave coswt can be classified into an audible wave band that can be heard by the human ear, an ultra-low frequency band whose frequency is below the audible wave, and an ultra-high frequency band whose frequency is above the audible wave. It becomes noise because it is heard in the ear. At very low frequencies, there are adverse effects on the human body such as headaches and nausea. Further, when the modulated wave having the carrier wave component caswt is demodulated using the non-linear characteristic, the non-linear characteristic is generally expressed by the equation (1) with respect to the input x. y = a 0 + a 1 x + a 2 x 2 + a 3 x 3 + ... (1) When a signal with a carrier component coswt is input here, it is output and cos 2 wt, as shown in equation (2), The term of cos 3 wt, ... Appears, and the terms of the second or higher order produce high frequencies of frequencies 2 wt, 3 wt ,. In a general demodulation circuit, high frequency components can be cut by a filter. Further, if the carrier wave is an ultra-high frequency, the harmonic component becomes an ultrasonic wave (inaudible) having a higher frequency, which is not a problem. If the carrier wave is an extremely low frequency, harmonics having an audible frequency will appear as noise. Therefore, the carrier band uses ultra high frequencies. In addition, since this ultra-high frequency has a large attenuation when propagating in the air, the attenuation of the reflection is large and the influence of the reflected wave can be suppressed. On the other hand, when the voice signal v (t) is amplitude-modulated (AM) by the balanced modulator 10 with the superhigh frequency carrier wave Acoswt, it is modulated into the form of the expression (3). f 1 (t) = A 0 {1 + kv (t)} coswt (3) Substituting this into the equation (1) of the nonlinear characteristic, The expression (4) is obtained, and a component (a 2 A 0 2 kv (t)) proportional to the audio signal v (t) appears, which does not serve as encryption by ultrasonic modulation. Therefore, the difference in modulation wave f 2 (t) = A 0 in which the phase of the general amplitude modulation wave f 1 (t) = A 0 {1 + kv (t)} coswt (3) is reversed by the balanced modulator 10 {1-kv (t)} coswt (5) When carrier suppression modulation is taken, the carrier suppression modulation wave is expressed by equation (6). f (t) = f 1 ( t) -f 2 (t) = 2A 0 kv (t) coswt = k 0 v (t) coswt ...... (6) ( however, k 0 = 2A 0 k) this suppression modulation When the wave k 0 v (t) coswt is input to the nonlinear characteristic of the equation (1), the equation becomes as shown in the equation (7).
Since the component (t) does not appear, the voice signal v (t) is modulated by the balanced modulator 10 by the carrier suppression modulation method. Therefore, as shown in FIG. 1, the suppression modulator wave k 0 v (t) coswt is output from the speaker 14 while the carrier generator 12 synchronizes with the carrier coswt output to the balance modulator 10. While carrying out, the carrier wave coswt is output from the speaker 16. Then, the suppression modulation wave k 0 v (t) coswt interferes with the carrier coswt, and at the interference point, a composite wave {1 + k 0 v (t)} coswt is obtained as shown in equation (8). k 0 v (t) coswt + coswt = {1 + k 0 v (t)} coswt ...
(8) Here, this composite wave {1 + k 0 v (t)} coswt is input to the nonlinear characteristic of the ear of the caller 18 in space to obtain the expression (9). Here, since the fifth and subsequent terms are ultrasonic waves that are carrier waves and their harmonic components, they are inaudible to the human ear. Also, the first
The term and the second term are DC components and are inaudible. Therefore, what is captured by the caller 18 as a demodulated signal is It is. Here, the second term is demodulation distortion and becomes noise, but the influence can be reduced by adjusting the value of k 0 . In addition, the distance from the speakers 14 and 16 is suppressed by the modulated wave k 0 v
(T) It must be set to an integral multiple of the wavelength so that the phase of coswt and the carrier wave coswt do not shift. Also, the suppression modulation wave k 0 v (t) c output from each of the speakers 14 and 16
The interference points between oswt and carrier coswt must be distributed on a plane. As shown in FIG. 2, generally, sound waves emitted from certain sound sources 20 and 22 are transmitted as spherical waves. Then, the transmission time of each point A, B, C on the interference surface is T A ,
When T B and T C are set, the transmission time becomes T A <T B <T C , and a transmission delay occurs. Therefore, as shown in FIG. 3, the interference points are distributed on the plane by using a speaker that generates a plane wave in which the transmission time of each point A, B, C becomes T A = T B = T C. On the other hand, since the periodic function coswt is used for the carrier wave, the interference surface exists not at the midpoint of the two speakers 14 and 16 but at the wavelength interval of the carrier wave (interference fringe phenomenon). Therefore, since each interference surface has a time lag, if the left and right ears are located on different interference surfaces, the sound heard by the left and right ears will wait for the time lag, and the distance between the ears will be 17 cm. The time lag is 5 × 10 -4 sec from Eq. (11). However, the overlapping of the interference surfaces can be regarded as one area because the distance between the interference surfaces becomes very short and the time shift can be ignored. Further, as shown in FIGS. 4 to 6, the plurality of interference surfaces are overlapped in different directions depending on the installation directions of the speakers 14 and 16 (vertical, front and rear, left and right). When the speakers 14 and 16 are installed above and below the talker 18 as shown in FIG. 4, the interference planes are horizontally overlapped and the left and right ears are on the same interference plane, so that the planes can be moved. However, there are many obstacles such as chairs against your sound waves from below and your body. In addition, as shown in FIG.
When installed on the left and right of the, the interference surface is parallel to the side surface of the body, so the left and right ears are on different interference surfaces. Also, one's head becomes an obstacle against sound waves. In addition, as shown in FIG.
When installed before and after, the interference surface is parallel to the front surface of the body, and the left and right ears are on the same interference surface, so that one's body is unlikely to interfere with sound waves. From the above, it is preferable to install the speakers 14 and 16 before and after the caller 18. As described above, by applying the broadcast space limiting device of the present invention to a telephone system, an audio signal is modulated by ultrasonic waves which are inaudible waves and demodulated only in a specific area where a caller is present. Therefore, it is possible to realize wireless and device-less without requiring a device such as a handset or a headphone. In addition, the confidentiality of the telephone is lost due to the modulation by the inaudible wave, such as a speakerphone, and the noise (noiselessness, confidentiality) can be measured without being heard by a person other than the caller to be noise and noise. [Effect of the Invention] As described above, according to the present invention, only a person who enters a space in which a modulated wave and a carrier interfere with each other can be identified as a voice. Inaudible. Therefore, the effect that the sound can be limited to an arbitrary space is obtained. Further, since the modulated wave and the carrier wave are respectively output as plane waves, the interference points are distributed on the plane and no transmission delay occurs on this plane.

【図面の簡単な説明】 第1図は本発明の放送空間の限定装置を示す概略構成
図、第2図および第3図はスピーカを示す概略構成図、
第4図乃至第6図はスピーカの配置を示す説明図であ
る。 14、16……スピーカ。
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram showing a broadcast space limiting device of the present invention, and FIGS. 2 and 3 are schematic configuration diagrams showing a speaker.
4 to 6 are explanatory views showing the arrangement of the speakers. 14, 16 …… Speaker.

Claims (1)

(57)【特許請求の範囲】 1.通話者のみが存在する開放された任意の空間内の特
定の可聴領域にのみ音声を限定する放送空間の限定装置
であって、 2つの超高周波の搬送波を同期させて発生可能な搬送波
発生手段と、 前記搬送波発生手段によって発生された搬送波の一方を
用いて、入力される音声信号を変調する変調手段と、 前記変調手段によって変調された変調波を平面波として
出力する第1のスピーカと、 前記第1のスピーカから前記搬送波の波長の整数倍の間
隔をあけて対面して配置され、前記搬送波発生手段によ
り発生された搬送波の他方を平面波として出力する第2
のスピーカと、 を有することを特徴とする放送空間の限定装置。
(57) [Claims] A broadcasting space limiting device for limiting audio only to a specific audible region in an open arbitrary space where only a caller exists, and a carrier generating unit capable of generating two ultra high frequency carriers in synchronization with each other. A modulating unit that modulates an input audio signal using one of the carrier waves generated by the carrier generating unit; a first speaker that outputs the modulated wave modulated by the modulating unit as a plane wave; A second speaker which is arranged facing each other from the first speaker with an interval which is an integral multiple of the wavelength of the carrier wave and which outputs the other of the carrier waves generated by the carrier wave generating means as a plane wave.
And a speaker for the broadcast space.
JP62071125A 1987-03-25 1987-03-25 Broadcast space limiting device Expired - Fee Related JP2688051B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP62071125A JP2688051B2 (en) 1987-03-25 1987-03-25 Broadcast space limiting device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP62071125A JP2688051B2 (en) 1987-03-25 1987-03-25 Broadcast space limiting device

Publications (2)

Publication Number Publication Date
JPS63236500A JPS63236500A (en) 1988-10-03
JP2688051B2 true JP2688051B2 (en) 1997-12-08

Family

ID=13451533

Family Applications (1)

Application Number Title Priority Date Filing Date
JP62071125A Expired - Fee Related JP2688051B2 (en) 1987-03-25 1987-03-25 Broadcast space limiting device

Country Status (1)

Country Link
JP (1) JP2688051B2 (en)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4525145B2 (en) * 2004-04-05 2010-08-18 ソニー株式会社 Acoustic device and method for controlling acoustic device
KR100912078B1 (en) * 2007-05-02 2009-08-12 한국전자통신연구원 Human body sound transmission system and method using single sound source
KR100942705B1 (en) * 2008-07-30 2010-02-16 한국전자통신연구원 Single sound transmission apparatus using human body-communication
JP4939636B2 (en) * 2009-08-06 2012-05-30 韓國電子通信研究院 Apparatus and method for transmitting a human body sound for minimizing signal loss
US9319802B2 (en) 2012-09-13 2016-04-19 Turtle Beach Corporation Personal audio system and method
JP6268909B2 (en) * 2013-10-21 2018-01-31 株式会社Soken Acoustic system and ultrasonic filter

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5595500A (en) * 1979-01-16 1980-07-19 Akira Sasaki Acoustic unit utilizing ultrasonic wave
JPS5952999A (en) * 1982-09-20 1984-03-27 Yoshimichi Yonezawa Synthesizing method of audible sound source

Also Published As

Publication number Publication date
JPS63236500A (en) 1988-10-03

Similar Documents

Publication Publication Date Title
KR100561094B1 (en) Loudspeaker device and method for driving the same, and audio signal transmitter/receiver
EP1175812B1 (en) Method for the reproduction of sound waves using ultrasound loudspeakers
EP0719493B1 (en) Apparatus and method for reducing acoustic feedback
US7146011B2 (en) Steering of directional sound beams
US4118599A (en) Stereophonic sound reproduction system
RU2569914C2 (en) Driving parametric loudspeakers
PL95268B1 (en) RECOVERY SYSTEM
JP2688051B2 (en) Broadcast space limiting device
JPH02265400A (en) Loudspeaker
KR20140087926A (en) System and Method for Personal Position Directed Speaker
CN109640229A (en) A kind of method reducing directional loudspeaker noise and the directional loudspeaker for reducing noise
US20030039370A1 (en) Method and apparatus for eliminating audio feedback
Nakayama et al. Synchronized amplitude-and-frequency modulation for a parametric loudspeaker
JPH08149592A (en) Parametric speaker controller
CN209642950U (en) A kind of directional loudspeaker reducing noise
KR20140011784A (en) System and method for personal position directed speaker and computer-readable recording medium with program therefor
US6466674B1 (en) Method and apparatus for eliminating audio feedback
JP3947649B2 (en) Method and apparatus for generating audible sonic waves by ultrasonic synthesis
Geng et al. Development of multi-way parametric array loudspeaker using multiplexed double sideband modulation
JPS629397A (en) Method and apparatus for reducing low frequency noise
CN104703086B (en) It is a kind of that sound system is oriented from silence based on active demodulation
Mori et al. Evaluation of thermal runaway control based on frequency modulated carrier wave in parametric array loudspeaker
KR100626521B1 (en) Sound output apparatus in using hypersonic in a mobile communication terminal
JPS6128293A (en) Parametric array speaker
Shimokata et al. High Attenuated Audio-beam Based on Near-focused Sideband Wave with Parametric Array Loudspeakers

Legal Events

Date Code Title Description
LAPS Cancellation because of no payment of annual fees