Patent Publication Number: US-11386880-B2

Title: Acoustic output apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. National Phase of International Patent Application No. PCT/JP2018/026734 filed on Jul. 17, 2018, which claims priority benefit of Japanese Patent Application No. JP 2017-157640 filed in the Japan Patent Office on Aug. 17, 2017. Each of the above-referenced applications is hereby incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present technology relates to an acoustic output apparatus having a detection microphone for detecting noise. 
     BACKGROUND ART 
     An acoustic output apparatus is available that is worn on a head or an ear for use as a headphone or an earphone to output a sound from a speaker. 
     Such an acoustic output apparatus should preferably be maintained in a high-quality output state, and it is particularly desirable that a sound output from the speaker with minimal noise should reach eardrums. 
     For such an acoustic output apparatus described above, a noise cancelling type has been developed that provides reduced noise (refer, for example, to PTL 1). 
     Such a noise cancelling type of acoustic output apparatus receives an external sound through a detection microphone for noise detection and outputs a noise cancelling signal that allows a user to perceive a sensation that noise detected by the detection microphone for noise detection is minimal. 
     The user perceives a sensation that the noise has been cancelled as a result of output of the noise cancelling signal, thus ensuring that the user hears a high-quality sound with minimal noise. 
     CITATION LIST 
     [Patent Literature] 
     [PTL 1] 
     Japanese Patent Laid-Open No. 2017-34702 
     SUMMARY 
     Technical Problem 
     Incidentally, an acoustic output apparatus such as a headphone or an earphone is used not only in a stationary stereo set or the like but also in a mobile phone, a compact music reproduction apparatus, and so on, and widespread use of mobile phones and other apparatuses in recent years has witnessed an increasing number of aspects in which acoustic output apparatuses are used outdoors in addition to aspects in which acoustic output apparatuses are used indoors. Therefore, it is particularly desirable that a high-quality output state with reduced external noise should be maintained in accordance with outdoor usage conditions. 
     In light of the foregoing, it is an object of the acoustic output apparatus of the present technology to overcome the above problem and provide an improved noise cancelling function. 
     Solution to Problem 
     Firstly, an acoustic output apparatus according to the present technology includes a detection microphone for detecting noise having an input vibrating plate, a speaker having an output vibrating plate, and a housing accommodating at least the speaker and the detection microphone therein. The input vibrating plate and the output vibrating plate are disposed approximately in a same orientation. 
     This ensures that a sound is output from the speaker while a sound is input to the detection microphone with the input vibrating plate and the output vibrating plate facing each other, thus making it possible to bring the input vibrating plate and the output vibrating plate closer to each other. As a result, it is less likely for a phase lag to take place between the sound output from the speaker and the sound input to the detection microphone. 
     Secondly, it is desirable that at least part of the detection microphone should be located to be opposed to the speaker in the above acoustic output apparatus. 
     As a result, part of the detection microphone faces the speaker. 
     Thirdly, it is desirable that the detection microphone as a whole should be located to be opposed to the speaker in the above acoustic output apparatus. 
     As a result, the detection microphone as a whole faces the speaker. 
     Fourthly, it is desirable that a distance between the detection microphone and the speaker should be equal to or less than a radius of the detection microphone in the above acoustic output apparatus. 
     This makes it unlikely, since the distance between the detection microphone and the speaker is small, for a phase lag to take place between the sound output from the speaker and the sound input to the detection microphone. 
     Fifthly, it is desirable that a sound output device should be provided to output a sound that differs in frequency band from a sound output from the speaker in the above acoustic output apparatus. 
     This makes it possible, even in the case where the speaker may diminish in its capability to output sounds in a specific band, for the user to hear excellent sounds in a broad band by a sound in the specific band output from the sound output device. 
     Sixthly, it is desirable that an opening should be formed in the housing and that a sensing microphone should be provided to detect noise input from the opening in the above acoustic output apparatus. 
     This ensures that noise is detected not only by the detection microphone but also by the sensing microphone, thus enhancing a noise reduction characteristic. 
     Seventhly, it is desirable that the sensing microphone should be provided inside the housing and that the detection microphone should be located on an opposite side of the sensing microphone with the speaker provided therebetween in the above acoustic output apparatus. 
     This ensures that the detection microphone and the sensing microphone are located on the opposite sides to each other with the speaker provided therebetween inside the housing. 
     Eighthly, it is desirable that a bracket should be provided that has a sound conduit through which the sound output from the speaker passes and that the speaker and the detection microphone should be attached to the bracket in the above acoustic output apparatus. 
     This eliminates the need for dedicated members for attaching the speaker and the detection microphone, respectively, because the speaker and the detection microphone are attached to the same member. 
     Ninthly, it is desirable that a sound output device should be provided to output a sound that differs in frequency band from the sound output from the speaker and that the sound output device should be attached to the bracket in the above acoustic output apparatus. 
     This ensures that the speaker, the detection microphone, and the sound output device are all attached to the same member, thus eliminating the need for dedicated members for attaching the speaker, the detection microphone, and the sound output device, respectively. 
     Tenthly, it is desirable that the sound output from the sound output device should pass through the sound conduit in the above acoustic output apparatus. 
     This ensures that the sound output from the speaker and the sound output from the sound output device are both output externally through the sound conduit, thus eliminating the need for separate sound conduits through which the sound output from the speaker and the sound output from the sound output device pass, respectively. 
     Eleventhly, another sound output apparatus according to the present technology includes a detection microphone for detecting noise having an input vibrating plate, a speaker having an output vibrating plate, and a housing accommodating at least the speaker and the detection microphone therein. The speaker has its axis extending approximately in a same direction as an axis of the detection microphone. 
     This ensures that a sound is output from the speaker while a sound is input to the detection microphone with the speaker having its axis extending approximately in the same direction as the axis of the detection microphone, thus making it possible to bring the speaker and the detection microphone closer to each other. As a result, it is less likely for a phase lag to take place between the sound output from the speaker and the sound input to the detection microphone. 
     Advantageous Effect of Invention 
     According to the present technology, a sound is output from a speaker while a sound is input to a detection microphone with an input vibrating plate and an output vibrating plate facing each other, thus making it possible to bring the input vibrating plate and the output vibrating plate closer to each other. As a result, it is less likely for a phase lag to take place between the sound output from the speaker and the sound input to the detection microphone. This provides higher noise detection accuracy of the detection microphone, thus contributing to an improved noise cancelling function. 
     It should be noted that the effect recited in the present specification are merely illustrative and not restrictive, and there may be other effects. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  illustrates, together with  FIGS. 2 to 8 , an embodiment of an acoustic output apparatus of the present technology, and  FIG. 1  is a perspective view of the acoustic output apparatus. 
         FIG. 2  is an exploded perspective view of the acoustic output apparatus. 
         FIG. 3  is an enlarged sectional view of the acoustic output apparatus. 
         FIG. 4  is an enlarged side view of the acoustic output apparatus. 
         FIG. 5  is an enlarged rear view illustrating a bracket and a cap. 
         FIG. 6  is an enlarged perspective view illustrating part of an internal structure, etc. 
         FIG. 7  is a side view illustrating an example in which part of a detection microphone is located to be opposed to a speaker. 
         FIG. 8  is a side view illustrating an example in which the detection microphone is located not to be opposed to the speaker. 
     
    
    
     DESCRIPTION OF EMBODIMENT 
     A description will be given below of a mode for carrying out an acoustic output apparatus of the present technology with reference to attached drawings. 
     In an embodiment described below, the acoustic output apparatus of the present technology is applied to an earphone. It should be noted, however, that the range of application of the present technology is not limited to an earphone and the present technology is widely applicable to a variety of other acoustic output apparatuses such as a headphone. 
     It should be noted that the acoustic output apparatus illustrated below has not only a speaker and a sound output device as sound output sections but also a sound conduit through which sounds output respectively from the speaker and the sound output device pass. In the description given below, longitudinal, horizontal, and vertical directions are represented by assuming that the sound conduit has its axial direction extending longitudinally and that the speaker and the sound output device are disposed vertically side by side. 
     It should be noted, however, that the longitudinal, horizontal, and vertical directions illustrated below are provided for convenience of explanation and that the directions are not limited thereto in carrying out the present technology. 
     &lt;Configuration of The Acoustic Output Apparatus&gt; 
     A description will be given below of a configuration of an acoustic output apparatus  1  (refer to  FIGS. 1 to 6 ). The acoustic output apparatuses  1  are used, for example, in pairs, and one of the pairs is used for the left ear, and the other is used for the right ear. It should be noted, however, that only the one acoustic output apparatus  1  may be used to hear sounds. 
     The acoustic output apparatus  1  includes various necessary sections inside and outside a housing  2 , and the housing  2  includes a front cover  3 , a middle cover  4 , and a rear cover  5  that are joined together from the front in sequence (refer to  FIGS. 1 to 3 ). 
     The front cover  3  has a cover surface section  3   a , a joint surface section  3   b , and a holding tube section  3   c . The cover surface section  3   a  is open rearward and approximately in the shape of a bowl. The joint surface section  3   b  protrudes rearward from a portion of the cover surface section  3   a  close to its periphery. The holding tube section  3   c  protrudes forward from the cover surface section  3   a . The joint surface section  3   b  is formed approximately in the shape of an arc surface and protrudes rearward from the portion of the cover surface section  3   a  close to its periphery with the exception of a lower end portion. 
     The middle cover  4  is formed in the shape of a tube having its axial direction extending longitudinally and has approximately the same outer size and shape as the cover section  3   a . The middle cover  4  has a vent hole  4   a  at its lower end portion (refer to  FIG. 4 ). 
     The rear cover  5  has a rear surface section  5   a , a circumferential surface section  5   b , a joint surface section  5   c , an insertion tube section  5   d , and an attachment tube section  5   e  (refer to  FIGS. 1 to 3 ). 
     The rear surface section  5   a  is formed in an annular shape having its axial direction extending longitudinally. An inner space of the rear surface section  5   a  is formed as an opening  5   f . The circumferential surface section  5   b  protrudes forward from a peripheral portion of the rear surface section  5   a  and is formed in such a shape that an outer shape thereof increases toward the front. The joint surface section  5   c  protrudes forward from a front end portion of the circumferential surface section  5   b  with the exception of the lower end portion. The insertion tube section  5   d  is formed in a cylindrical shape that protrudes downward from the lower end portion of the circumferential surface section  5   b . The attachment tube section  5   e  is formed in a cylindrical shape that protrudes forward from the rear surface section  5   a.    
     The housing  2  is formed by joining a front end portion of the middle cover  4  with the joint surface section  3   b  of the front cover  3  such that the front end portion of the middle cover  4  is fitted onto the joint surface section  3   b  and by joining a rear end portion of the middle cover  4  with the joint surface section  5   c  of the rear cover  5  such that the rear end portion of the middle cover  4  is fitted onto the joint surface section  5   c.    
     The housing  2  has a bracket  6 , and part of the bracket  6  protrudes forward from the holding tube section  3   c . The bracket  6  has a first attachment section  7 , a second attachment section  8 , and a sound conduit  9 . 
     The first attachment section  7  has a base surface section  10  and a tube surface section  11 . The base surface section  10  is disposed in a longitudinal orientation and approximately in the shape of a disk. The tube surface section  11  protrudes rearward from a peripheral portion of the base surface section  10 . A sound input hole  10   a , an adjustment hole  10   b , and a first sound passage hole  10   c  are formed in this order from top in the base surface section  10  (refer to  FIG. 5 ). 
     Formed in the shape of a case that extends longitudinally and is open rearward, the second attachment section  8  is located under the first attachment section  7 , and an approximately rear half portion of the second attachment section  8  vertically is continuous with the first attachment section  7  (refer to  FIGS. 2, 3, and 5 ). A second sound passage hole  8   a  that penetrates a front half portion of the second attachment section  8  is formed in an upper surface section of the second attachment section  8 . 
     The sound conduit  9  has a sound tube section  9   a  and a partitioning plate  9   b . The sound tube section  9   a  has its axial direction extending longitudinally and is approximately in a cylindrical shape. The partitioning plate  9   b  is located inside the sound tube section  9   a . The sound conduit  9  protrudes forward from a lower end portion of the base surface section  10 , and an approximately rear half portion of the sound conduit  9  is continuous with an approximately front half portion of the second attachment section  8 . A first sound passage hole  10   c  of the base surface section  10  communicates with the second sound passage hole  8   a  of the second attachment section  8  in an inner space of the sound tube section  9   a . The partitioning plate  9   b  is disposed in a vertical orientation and protrudes forward from a lower opening edge of the first sound passage hole  10   c  formed in the base surface section  10 , and left and right side edges thereof are continuous with an inner surface of the sound tube section  9   a , respectively. Therefore, part of the inner space of the sound conduit  9  is partitioned vertically by the partitioning plate  9   b.    
     The portion of the bracket  6  other than a front end portion of the sound conduit  9  is provided inside the housing  2 , and the sound tube section  9   a  is held in a manner inserted in the holding tube section  3   c  of the front cover  3 . A front end portion of the sound tube section  9   a  of the bracket  6  protrudes forward from the holding tube section  3   c.    
     An equalizer  12  is provided in a manner press-fitted into the front end portion of the sound tube section  9   a . The equalizer  12  includes, for example, compressed urethane and primarily has a function to adjust, of the sounds that pass through the sound tube section  9   a , the extent to which high frequencies are attenuated. 
     A detection microphone  13 , a register  14 , and a speaker  15  are attached to the first attachment section  7  of the bracket  6 . 
     The detection microphone  13  functions as a feedback microphone for detecting noise near an ear and is attached at a position where the detection microphone  13  covers the sound input hole  10   a  on the front surface of the base surface section  10 . The detection microphone  13  has an input vibrating plate  13   a  that is formed circular in outer shape and disposed approximately in a longitudinal orientation. 
     The register  14  is formed, for example, in an annular shape and attached to a rear surface of the base surface section  10  with a center hole  14   a  located immediately behind the adjustment hole  10   b . The register  14  primarily has a function to adjust, of the sounds output from the speaker  15 , the sensitivity to low-frequency sounds. The center hole  14   a  of the register  14  is smaller in diameter than the adjustment hole  10   b  of the base surface section  10 . 
     The speaker  15  is attached to the bracket  6  with a front portion of the speaker  15  inserted in the first attachment section  7 . The speaker  15  has an output vibrating plate  15   a  that is formed circular in outer shape and orientated approximately longitudinally. 
     As described above, the detection microphone  13  is attached to the front surface of the base surface section  10 , the speaker  15  is attached to the rear surface of the base surface section  10 , and the detection microphone  13  is located right in front of the speaker  15 . Therefore, the detection microphone  13  as a whole is located to be opposed to the speaker  15 . The input vibrating plate  13   a  of the detection microphone  13  and the output vibrating plate  15   a  of the speaker  15  are both oriented approximately longitudinally and disposed approximately in the same orientation. The speaker  15  can output sounds in a wide range of low to high frequencies. 
     With the detection microphone  13  and the speaker  15  attached to the bracket  6 , a distance between the detection microphone  13  and the speaker  15  is equal to or less than a radius of the detection microphone  13 . Specifically, for example, the radius of the detection microphone  13  is 2 mm, and the distance between the detection microphone  13  and the speaker  15  is equal to or less than 1 mm. 
     Also, the detection microphone  13  (direction of a central axis S 1 ) and the speaker  15  (direction of a central axis S 2 ) both have their axes extending longitudinally, and the detection microphone  13  and the speaker  15  have their axes extending approximately in the same direction. 
     A sound absorbing material  16  is attached to a rear surface of the speaker  15 . The sound absorbing material  16  includes, for example, compressed urethane and primarily has a function to adjust, of the sounds output from the speaker  15 , the sensitivity to medium and low frequencies. 
     With the speaker  15  attached to the bracket  6 , part of the speaker  15  protrudes rearward from the first attachment section  7 , and this protruding portion is covered by a speaker cover  17 . A disposition hole  17   a  is formed in the speaker cover  17 . The speaker cover  17  is attached, from the rear, to the first attachment section  7  of the bracket  6  in such a manner as to cover the speaker  15  from the rear. With the speaker  15  covered by the speaker cover  17 , the sound absorbing material  16  is disposed in the disposition hole  17   a.    
     A sound output device  18  is attached to the second attachment section  8  of the bracket  6 . A microphone unit  20  is located in a region posterior to the speaker  15 . The sound output device  18  is disposed in a manner inserted in the second attachment section  18  from the rear. The sound output device  18  functions, for example, as a tweeter and outputs high-frequency sounds that differ in frequency band from the sounds output from the speaker  15 . 
     A circuit board  19  is attached to a rear surface of the speaker cover  17 . The circuit board  19  drives and controls the speaker  15  and the sound output device  18 . 
     The microphone unit  20  is attached to the attachment tube section  5   e  of the rear cover  5 . The microphone unit  20  has a sensing microphone  20   a , a microphone casing  20   b , and a microphone sheet  20   c . The sensing microphone  20   a  is covered by the microphone casing  20   b  from the front, and the microphone sheet  20   c  is attached to a rear surface of the sensing microphone  20   a . The sensing microphone  20   b  is attached to the attachment tube section  5   e  inside the housing  2  to function as a feedforward microphone for detecting noise input from the opening  5   f  at a peripheral side position of the acoustic output apparatus  1 . 
     A bushing  21  is inserted into and attached to the insertion tube section  5   d  of the rear cover  5 . A cable  22  is sheathed inside the bushing  21 , and the cable  22  is connected to the circuit board  19 , the detection microphone  13 , and the sensing microphone  20   a.    
     A cap  23  is attached to the portion of the sound conduit  9  that protrudes forward from the holding tube section  3   c  of the front cover  3 . The cap  23  includes a rubber material, etc. and is inserted into an ear hole when a user uses the acoustic output apparatus  1 . A passage hole  23   a  that communicates with the inner space of the sound conduit  9  is formed in the cap  23 . 
     As described above, in the acoustic output apparatus  1 , the sensing microphone  20   a  is disposed in the housing  2 , and the detection microphone  13  and the sensing microphone  20   a  are located on the opposite sides to each other with the speaker  15  provided therebetween. 
     Therefore, because the detection microphone  13  and the sensing microphone  20   a  are located on the opposite sides to each other with the speaker  15  provided therebetween inside the housing  2 , the acoustic output apparatus  1  can be downsized through effective use of the space. 
     Also, the bracket  6  is provided that has the sound conduit  9  to permit passage of sounds output from the speaker  15 , and the speaker  15  and the detection microphone  13  are attached to the bracket  6 . 
     Therefore, the speaker  15  and the detection microphone  13  are attached to the same member, thus eliminating the need for dedicated members for attaching the speaker  15  and the detection microphone  13 , respectively, and ensuring further downsizing of the acoustic output apparatus  1  through reduced parts count. 
     Further, the sound output device  18  is attached to the bracket  6 . As a result, the speaker  15 , the detection microphone  13 , and the sound output device  18  can all be attached to the same member, thus eliminating the need for dedicated members for attaching the speaker  15 , the detection microphone  13 , and the sound output device  18 , respectively, and ensuring further downsizing of the acoustic output apparatus  1  through reduced parts count. 
     &lt;Operation of The Acoustic Output Apparatus&gt; 
     In the acoustic output apparatus  1  configured as described above, when a sound is output from the speaker  15 , the output sound passes through the sound conduit  9  from the first sound passage hole  10   c  of the base surface section  10 . At this time, the sound passes above the partitioning plate  9   a  in the sound conduit  9  and reaches the user&#39;s eardrum via the passage hole  23   a  of the cap  23 . 
     At the same time, a sound is also output from the sound output device  18 , and the output sound passes through the sound conduit  9  from the second sound passage hole  8   a  of the second attachment section  8 . At this time, the sound passes below the partitioning plate  9   a  in the sound conduit  9  and reaches the user&#39;s eardrum via the passage hole  23   a  of the cap  23 . 
     The sounds that are output from the speaker  15  and the sound output device  18  and pass through the sound conduit  9  are adjusted by the equalizer  12  in terms of the extent to which high frequencies are attenuated, thus allowing a sound whose high frequencies have properly been adjusted reaches the eardrum. 
     As described above, the sound output from the sound output device  18  passes through the sound conduit  9 . 
     Therefore, the sounds that are output from the speaker  15  and the sound output device  18  are both externally output through the sound conduit  9 , thus eliminating the need for separate sound conduits through which the sound output from the speaker  15  and the sound output from the sound output device  18  pass, respectively, ensuring downsizing of the acoustic output apparatus  1  through reduced parts count, and contributing to reduced manufacturing cost. 
     When a sound is output from the speaker  15 , the output sound not only passes through the sound conduit  9  but also is input to the detection microphone  13  from the sound input hole  10   a  of the base surface section  10 . 
     Also, at the same time, the sound output from the speaker  15  passes through the center hole  14   a  of the register  14  via the adjustment hole  10   b  of the base surface section  10 . At the same time, the sensitivity to low frequencies is adjusted by the register  14 . The sound that has passed through the center hole  14   a  of the register  14  is guided downward through the inner side of the front cover  3  and released externally from the vent hole  4   a  of the middle cover  4 . 
     Further, when a sound is output from the speaker  15 , the sound is also output rearward, and the sensitivity to medium and low frequencies is adjusted by the sound absorbing material  16 . At least part of the sound output rearward from the speaker  15  is guided downward and released externally from the vent hole  4   a  of the middle cover  4 . 
     When sounds are output from the speaker  15  and the sound output device  18  at the same time, a noise cancelling function is activated by the detection microphone  13  and the sensing microphone  20   a . The noise cancelling function primarily detects noise in the sound passing through the sound conduit  9  with the detection microphone  13 , detects noise in external sounds with the sensing microphone  20   a , and then generates, with a noise cancelling circuit which is not illustrated, a noise cancelling signal that causes the user to perceive that each detected noise is minimal. 
     Since the noise cancelling signal is generated, the user perceives that the noise detected by the detection microphone  13  and the sensing microphone  20   a , respectively, have been cancelled, thus hearing high-quality sounds with minimal noise. 
     &lt;Conclusion&gt; 
     As described above, the acoustic output apparatus  1  has the detection microphone  13 , the speaker  15 , and the housing  2 . The detection microphone  13  has the input vibrating plate  13   a  for detecting noise. The speaker  15  has the output vibrating plate  15   a . The housing  2  accommodates at least the speaker  15  and the detection microphone  13  therein. The input vibrating plate  13   a  and the output vibrating plate  15   a  are disposed approximately in the same orientation. 
     Therefore, a sound is output from the speaker  15  while a sound is input to the detection microphone  13  with the input vibrating plate  13   a  and the output vibrating plate  15   a  facing each other, thus making it possible to bring the input vibrating plate and the output vibrating plate closer to each other. This makes it less likely for a phase lag to take place between the sound output from the speaker  15  and the sound input to the detection microphone  13 , thus providing higher noise detection accuracy of the detection microphone  13  and improving a noise cancelling function. 
     Also, the detection microphone  13  and the speaker  15  have their axes extending approximately in the same direction. 
     Therefore, a sound is output from the speaker  15  while a sound is input to the detection microphone  13  with the speaker  15  and the detection microphone  13  having their axes extending approximately in the same direction, thus making it possible to bring the speaker  15  and the detection microphone  13  closer to each other. This makes it less likely for a phase lag to take place between the sound output from the speaker  15  and the sound input to the detection microphone  13 , thus providing higher noise detection accuracy of the detection microphone  13  and contributing to an advanced noise cancelling function. 
     Further, the detection microphone  13  as a whole is located to be opposed to the speaker  15 . As a result, the detection microphone  13  as a whole faces the speaker  15 , thus contributing to an even more advanced noise cancelling function. 
     Further, the distance between the detection microphone  13  and the speaker  15  is equal to or less than the radius of the detection microphone  13 . This makes it even more unlikely, since the distance between the detection microphone  13  and the speaker  15  is small, for a phase lag to take place between the sound output from the speaker  15  and the sound input to the detection microphone  13 , thus contributing to an even more advanced noise cancelling function. 
     In addition, the sensing microphone  20   a  is provided to detect noise input from the opening  5   f  of the housing  2 . Therefore, noise is detected not only by the detection microphone  13  but also by the sensing microphone  20   a , thus providing a higher noise reduction characteristic and contributing to improved sound quality of the acoustic output apparatus  1 . 
     In the acoustic output apparatus  1 , the input vibrating plate  13   a  of the detection microphone  13  and the output vibrating plate  15   a  of the speaker  15  are disposed approximately in the same orientation as described above, thus providing higher noise detection accuracy of the detection microphone  13  and contributing to an improved noise cancelling function. 
     However, in the case where the noise cancelling function is improved by orienting the input vibrating plate  13   a  and the output vibrating plate  15   a  approximately in the same direction, the speaker  15  may diminish in output of sounds in a specific range such as high-frequency sounds. 
     For this reason, the sound output device  18  is provided in the acoustic output apparatus  1  to output a sound that differs in frequency band from the sound output from the speaker  15 . The sound output device  18  outputs high-frequency sounds, for example, as described above. As a result, even in the case where the speaker  15  may diminish in its capability to output high-frequency sounds, the user can hear excellent sounds in a wide range of low to high frequencies by high-frequency sounds output from the sound output device  18 . 
     As described above, the sound output device  18  is provided in the acoustic output apparatus  1  to output a sound that differs in frequency band from the sound output from the speaker  15 . Therefore, even in the case where the speaker  15  diminishes in its capability to output sounds in some frequency bands, it is possible for the sound output device  18  to output the sounds which the speaker  15  has diminished in its capability to output, thus making it possible to output a wide range of sounds. 
     &lt;Others&gt; 
     Although an example is illustrated above in which the detection microphone  13  as a whole is located to be opposed to the speaker  15 , part of the detection microphone  13  may be located to be opposed to the speaker  15  in the acoustic output apparatus  1  (refer to  FIG. 7 ). 
     Even in the case where part of the detection microphone  13  is located to be opposed to the speaker  15  as described above, part of the detection microphone  13  faces the speaker  15 , thus contributing to an excellent noise cancelling function. 
     Also, as long as the input vibrating plate  13   a  of the detection microphone  13  and the output vibrating plate  15   a  of the speaker  15  are disposed approximately in the same orientation, the detection microphone  13  as a whole may not be located to be opposed to the speaker  15  at all (refer to  FIG. 8 ). 
     Further, as long as the speaker  15  has its axis extending approximately in the same direction as the axis of the detection microphone  13 , the detection microphone  13  as a whole may not be located to be opposed to the speaker  15  at all. 
     As described above, orienting the input vibrating plate  13   a  of the detection microphone  13  and the output vibrating plate  15   a  of the speaker  15  approximately in the same direction or disposing the speaker  15  and the detection microphone  13  such that their axes extend approximately in the same direction makes it unlikely for a phase lag to take place between the sound output from the speaker  15  and the sound input to the detection microphone  13 , thus making it possible to improve the noise cancelling function. 
     &lt;Present Technology&gt; 
     The present technology can have the following configurations. 
     (1) An acoustic output apparatus including:
         a detection microphone for detecting noise having an input vibrating plate;   a speaker having an output vibrating plate; and a housing accommodating at least the speaker and the detection microphone therein, in which   the input vibrating plate and the output vibrating plate are disposed approximately in a same orientation.       

     (2) The acoustic output apparatus of feature (1), in which at least part of the detection microphone is located to be opposed to the speaker. 
     (3) The acoustic output apparatus of feature (2), in which the detection microphone as a whole is located to be opposed to the speaker. 
     (4) The acoustic output apparatus of any one of features (1) to (3), in which
         a distance between the detection microphone and the speaker is equal to or less than a radius of the detection microphone.       

     (5) The acoustic output apparatus of any one of features (1) to (4), in which
         a sound output device is provided to output a sound that differs in frequency band from a sound output from the speaker.       

     (6) The acoustic output apparatus of any one of features (1) to (5), in which
         an opening is formed in the housing, and   a sensing microphone is provided to detect noise input from the opening.       

     (7) The acoustic output apparatus of feature (6), in which the sensing microphone is provided inside the housing, and the detection microphone is located on an opposite side of the sensing microphone with the speaker provided therebetween. 
     (8) The acoustic output apparatus of any one of features (1) to (7), in which
         a bracket is provided that has a sound conduit through which the sound output from the speaker passes, and   the speaker and the detection microphone are attached to the bracket.       

     (9) The acoustic output apparatus of feature (8), in which
         a sound output device is provided to output a sound that differs in frequency band from the sound output from the speaker, and   the sound output device is attached to the bracket.       

     (10) The acoustic output apparatus of feature (9), in which the sound output from the sound output device passes through the sound conduit. 
     (11) A sound output apparatus including:
         a detection microphone for detecting noise having an input vibrating plate;   a speaker having an output vibrating plate; and   a housing accommodating at least the speaker and the detection microphone therein, in which   the speaker has its axis extending approximately in a same direction as an axis of the detection microphone.       

     REFERENCE SIGNS LIST 
       1  Acoustic output apparatus,  2  Housing,  5   f  Opening,  6  Bracket,  9  Sound conduit,  13  Detection microphone,  13   a  Input vibrating plate,  15  Speaker,  15   a  Output vibrating plate,  18  Sound output device,  20   a  Sensing microphone