Patent Publication Number: US-11641552-B2

Title: Bone conduction speaker and compound vibration device thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part application of U.S. patent application Ser. No. 17/170,817, filed on Feb. 8, 2021, which is a continuation of U.S. patent application Ser. No. 17/161,717, filed on Jan. 29, 2021, which is a continuation-in-part application of U.S. patent application Ser. No. 16/159,070 (issued as U.S. Pat. No. 10,911,876), filed on Oct. 12, 2018, which is a continuation of U.S. patent application Ser. No. 15/197,050 (issued as U.S. Pat. No. 10,117,026), filed on Jun. 29, 2016, which is a continuation of U.S. patent application Ser. No. 14/513,371 (issued as U.S. Pat. No. 9,402,116), filed on Oct. 14, 2014, which is a continuation of U.S. patent application Ser. No. 13/719,754 (issued as U.S. Pat. No. 8,891,792), filed on Dec. 19, 2012, which claims priority to Chinese Patent Application No. 201110438083.9, filed on Dec. 23, 2011; U.S. patent application Ser. No. 17/161,717, filed on Jan. 29, 2021 is also a continuation-in-part application of U.S. patent application Ser. No. 16/833,839, filed on Mar. 30, 2020, which is a continuation of U.S. application Ser. No. 15/752,452 (issued as U.S. Pat. No. 10,609,496), filed on Feb. 13, 2018, which is a national stage entry under 35 U.S.C. § 371 of International Application No. PCT/CN2015/086907, filed on Aug. 13, 2015; this application is also a continuation-in-part of U.S. patent application Ser. No. 17/170,955, filed on Feb. 9, 2021, which is a Continuation of International Application No. PCT/CN2020/083631, filed on Apr. 8, 2020, which claims priority to Chinese Application No. 201910888067.6, filed on Sep. 19, 2019, Chinese Application No. 201910888762.2, filed on Sep. 19, 2019, and Chinese Application No. 201910364346.2, filed on Apr. 30, 2019. Each of the above-referenced applications is hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to improvements on a bone conduction speaker and its components, in detail, relates to a bone conduction speaker and its compound vibration device, while the frequency response of the bone conduction speaker has been improved by the compound vibration device, which is composed of vibration boards and vibration conductive plates. 
     BACKGROUND 
     Based on the current technology, the principle that we can hear sounds is that the vibration transferred through the air in our external acoustic meatus, reaches to the ear drum, and the vibration in the ear drum drives our auditory nerves, makes us feel the acoustic vibrations. The current bone conduction speakers are transferring vibrations through our skin, subcutaneous tissues and bones to our auditory nerves, making us hear the sounds. 
     When the current bone conduction speakers are working, with the vibration of the vibration board, the shell body, fixing the vibration board with some fixers, will also vibrate together with it, thus, when the shell body is touching our post auricles, cheeks, forehead or other parts, the vibrations will be transferred through bones, making us hear the sounds clearly. 
     However, the frequency response curves generated by the bone conduction speakers with current vibration devices are shown as the two solid lines in  FIG.  4   . In ideal conditions, the frequency response curve of a speaker is expected to be a straight line, and the top plain area of the curve is expected to be wider, thus the quality of the tone will be better, and easier to be perceived by our ears. However, the current bone conduction speakers, with their frequency response curves shown as  FIG.  4   , have overtopped resonance peaks either in low frequency area or high frequency area, which has limited its tone quality a lot. Thus, it is very hard to improve the tone quality of current bone conduction speakers containing current vibration devices. The current technology needs to be improved and developed. 
     SUMMARY 
     The purpose of the present disclosure is providing a bone conduction speaker and its compound vibration device, to improve the vibration parts in current bone conduction speakers, using a compound vibration device composed of a vibration board and a vibration conductive plate to improve the frequency response of the bone conduction speaker, making it flatter, thus providing a wider range of acoustic sound. 
     The technical proposal of present disclosure is listed as below: 
     A compound vibration device in bone conduction speaker contains a vibration conductive plate and a vibration board, the vibration conductive plate is set as the first torus, where at least two first rods in it converge to its center. The vibration board is set as the second torus, where at least two second rods in it converge to its center. The vibration conductive plate is fixed with the vibration board. The first torus is fixed on a magnetic system, and the second torus contains a fixed voice coil, which is driven by the magnetic system. 
     In the compound vibration device, the magnetic system contains a baseboard, and an annular magnet is set on the board, together with another inner magnet, which is concentrically disposed inside this annular magnet, as well as an inner magnetic conductive plate set on the inner magnet, and the annular magnetic conductive plate set on the annular magnet. A grommet is set on the annular magnetic conductive plate to fix the first torus. The voice coil is set between the inner magnetic conductive plate and the annular magnetic plate. 
     In the compound vibration device, the number of the first rods and the second rods are both set to be three. 
     In the compound vibration device, the first rods and the second rods are both straight rods. 
     In the compound vibration device, there is an indentation at the center of the vibration board, which adapts to the vibration conductive plate. 
     In the compound vibration device, the vibration conductive plate rods are staggered with the vibration board rods. 
     In the compound vibration device, the staggered angles between rods are set to be 60 degrees. 
     In the compound vibration device, the vibration conductive plate is made of stainless steel, with a thickness of 0.1-0.2 mm, and, the width of the first rods in the vibration conductive plate is 0.5-1.0 mm; the width of the second rods in the vibration board is 1.6-2.6 mm, with a thickness of 0.8-1.2 mm. 
     In the compound vibration device, the number of the vibration conductive plate and the vibration board is set to be more than one. They are fixed together through their centers and/or torus. 
     A bone conduction speaker comprises a compound vibration device which adopts any methods stated above. 
     The bone conduction speaker and its compound vibration device as mentioned in the present disclosure, adopting the fixed vibration boards and vibration conductive plates, make the technique simpler with a lower cost. Also, because the two parts in the compound vibration device can adjust low frequency and high frequency areas, the achieved frequency response is flatter and wider, the possible problems like abrupt frequency responses or feeble sound caused by single vibration device will be avoided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    illustrates a longitudinal section view of the bone conduction speaker in the present disclosure; 
         FIG.  2    illustrates a perspective view of the vibration parts in the bone conduction speaker in the present disclosure; 
         FIG.  3    illustrates an exploded perspective view of the bone conduction speaker in the present disclosure; 
         FIG.  4    illustrates a frequency response curves of the bone conduction speakers of vibration device in the prior art; 
         FIG.  5    illustrates a frequency response curves of the bone conduction speakers of the vibration device in the present disclosure; 
         FIG.  6    illustrates a perspective view of the bone conduction speaker in the present disclosure; 
         FIG.  7    illustrates a structure of the bone conduction speaker and the compound vibration device according to some embodiments of the present disclosure; 
         FIG.  8   -A illustrates an equivalent vibration model of the vibration portion of the bone conduction speaker according to some embodiments of the present disclosure; 
         FIG.  8   -B illustrates a vibration response curve of the bone conduction speaker according to one specific embodiment of the present disclosure; 
         FIG.  8   -C illustrates a vibration response curve of the bone conduction speaker according to one specific embodiment of the present disclosure; 
         FIG.  9   -A illustrates a structure of the vibration generation portion of the bone conduction speaker according to one specific embodiment of the present disclosure; 
         FIG.  9   -B illustrates a vibration response curve of the bone conduction speaker according to one specific embodiment of the present disclosure; 
         FIG.  9   -C illustrates a sound leakage curve of the bone conduction speaker according to one specific embodiment of the present disclosure; 
         FIG.  10    illustrates a structure of the vibration generation portion of the bone conduction speaker according to one specific embodiment of the present disclosure; 
         FIG.  11   -A illustrates an application scenario of the bone conduction speaker according to one specific embodiment of the present disclosure; 
         FIG.  11   -B illustrates a vibration response curve of the bone conduction speaker according to one specific embodiment of the present disclosure; 
         FIG.  12    illustrates a structure of the vibration generation portion of the bone conduction speaker according to one specific embodiment of the present disclosure; 
         FIG.  13    illustrates a structure of the vibration generation portion of the bone conduction speaker according to one specific embodiment of the present disclosure; 
         FIG.  14    is a schematic diagram illustrating an exemplary acoustic output apparatus embodied as glasses according to some embodiments of the present disclosure; 
         FIG.  15    is a schematic diagram illustrating exemplary components in an acoustic output apparatus according to some embodiments of the present disclosure; 
         FIG.  16    is a schematic diagram illustrating a bluetooth low energy (BLE) module according to some embodiments of the present disclosure; 
         FIG.  17    is a flow chart illustrating an exemplary process for transmitting audio data to a terminal device through the BLE module according to some embodiments of the present disclosure; and 
         FIG.  18    is a flow chart illustrating an exemplary process for determining a location of the acoustic output apparatus using the BLE module according to some embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     A detailed description of the implements of the present disclosure is stated here, together with attached figures. 
     An acoustic output apparatus in the present disclosure may refer to a device having a sound output function. In practical applications, the acoustic output apparatus may be implemented by products of various types, such as speakers (e.g., bone conduction speakers), bracelets, glasses, helmets, watches, clothings, or backpacks. For illustration purposes, a bone conduction speaker and a pair of glasses with a sound output function may be provided as an example of the acoustic output apparatus. Exemplary glasses may include myopia glasses, sports glasses, hyperopia glasses, reading glasses, astigmatism lenses, wind/sand-proof glasses, sunglasses, ultraviolet-proof glasses, welding mirrors, infrared-proof mirrors, and virtual reality (VR) glasses, augmented Reality (AR) glasses, mixed reality (MR) glasses, mediated reality glasses, or the like, or any combination thereof. 
     As shown in  FIG.  1    and  FIG.  3   , the compound vibration device in the present disclosure of bone conduction speaker, comprises: the compound vibration parts composed of vibration conductive plate  1  and vibration board  2 , the vibration conductive plate  1  is set as the first torus  111  and three first rods  112  in the first torus converging to the center of the torus, the converging center is fixed with the center of the vibration board  2 . The center of the vibration board  2  is an indentation  120 , which matches the converging center and the first rods. The vibration board  2  contains a second torus  121 , which has a smaller radius than the vibration conductive plate  1 , as well as three second rods  122 , which is thicker and wider than the first rods  112 . The first rods  112  and the second rods  122  are staggered. In some embodiments, a staggered angle between one of the first rods  112  and one of the second rods  122  may be a predetermined angle. For example, the predetermined angle may include but not limited to an angle of 60 degrees, as shown in  FIG.  2   . A better solution is, both the first and second rods are all straight rods. 
     Obviously the number of the first and second rods can be more than two, for example, if there are two rods, they can be set in a symmetrical position; however, the most economic design is working with three rods. Not limited to this rods setting mode, the setting of rods in the present disclosure can also be a spoke structure with four, five or more rods. 
     The vibration conductive plate  1  is very thin and can be more elastic, which is stuck at the center of the indentation  120  of the vibration board  2 . Below the second torus  121  spliced in vibration board  2  is a voice coil  8 . The compound vibration device in the present disclosure also comprises a bottom plate  12 , where an annular magnet  10  is set, and an inner magnet  11  is set in the annular magnet  10  concentrically. An inner magnet conduction plate  9  is set on the top of the inner magnet  11 , while annular magnet conduction plate  7  is set on the annular magnet  10 , a grommet  6  is fixed above the annular magnet conduction plate  7 , the first torus  111  of the vibration conductive plate  1  is fixed with the grommet  6 . The whole compound vibration device is connected to the outside through a panel  13 , the panel  13  is fixed with the vibration conductive plate  1  on its converging center, stuck and fixed at the center of both vibration conductive plate  1  and vibration board  2 . 
     It should be noted that, both the vibration conductive plate and the vibration board can be set more than one, fixed with each other through either the center or staggered with both center and edge, forming a multilayer vibration structure, corresponding to different frequency resonance ranges, thus achieve a high tone quality earphone vibration unit with a gamut and full frequency range, despite of the higher cost. 
     The bone conduction speaker contains a magnet system, composed of the annular magnet conductive plate  7 , annular magnet  10 , bottom plate  12 , inner magnet  11  and inner magnet conductive plate  9 , because the changes of audio-frequency current in the voice coil  8  cause changes of magnet field, which makes the voice coil  8  vibrate. The compound vibration device is connected to the magnet system through grommet  6 . The bone conduction speaker connects with the outside through the panel  13 , being able to transfer vibrations to human bones. 
     In the better implement examples of the present bone conduction speaker and its compound vibration device, the magnet system, composed of the annular magnet conductive plate  7 , annular magnet  10 , inner magnet conduction plate  9 , inner magnet  11  and bottom plate  12 , interacts with the voice coil which generates changing magnet field intensity when its current is changing, and inductance changes accordingly, forces the voice coil  8  move longitudinally, then causes the vibration board  2  to vibrate, transfers the vibration to the vibration conductive plate  1 , then, through the contact between panel  13  and the post ear, cheeks or forehead of the human beings, transfers the vibrations to human bones, thus generates sounds. A complete product unit is shown in  FIG.  6   . 
     Through the compound vibration device composed of the vibration board and the vibration conductive plate, a frequency response shown in  FIG.  5    is achieved. The double compound vibration generates two resonance peaks, whose positions can be changed by adjusting the parameters including sizes and materials of the two vibration parts, making the resonance peak in low frequency area move to the lower frequency area and the peak in high frequency move higher, finally generates a frequency response curve as the dotted line shown in  FIG.  5   , which is a flat frequency response curve generated in an ideal condition, whose resonance peaks are among the frequencies catchable with human ears. Thus, the device widens the resonance oscillation ranges, and generates the ideal voices. 
     In some embodiments, the stiffness of the vibration board may be larger than that of the vibration conductive plate. In some embodiments, the resonance peaks of the frequency response curve may be set within a frequency range perceivable by human ears, or a frequency range that a person&#39;s ears may not hear. Preferably, the two resonance peaks may be beyond the frequency range that a person may hear. More preferably, one resonance peak may be within the frequency range perceivable by human ears, and another one may be beyond the frequency range that a person may hear. More preferably, the two resonance peaks may be within the frequency range perceivable by human ears. Further preferably, the two resonance peaks may be within the frequency range perceivable by human ears, and the peak frequency may be in a range of 80 Hz-18000 Hz. Further preferably, the two resonance peaks may be within the frequency range perceivable by human ears, and the peak frequency may be in a range of 200 Hz-15000 Hz. Further preferably, the two resonance peaks may be within the frequency range perceivable by human ears, and the peak frequency may be in a range of 500 Hz-12000 Hz. Further preferably, the two resonance peaks may be within the frequency range perceivable by human ears, and the peak frequency may be in a range of 800 Hz-11000 Hz. There may be a difference between the frequency values of the resonance peaks. For example, the difference between the frequency values of the two resonance peaks may be at least 500 Hz, preferably 1000 Hz, more preferably 2000 Hz, and more preferably 5000 Hz. To achieve a better effect, the two resonance peaks may be within the frequency range perceivable by human ears, and the difference between the frequency values of the two resonance peaks may be at least 500 Hz. Preferably, the two resonance peaks may be within the frequency range perceivable by human ears, and the difference between the frequency values of the two resonance peaks may be at least 1000 Hz. More preferably, the two resonance peaks may be within the frequency range perceivable by human ears, and the difference between the frequency values of the two resonance peaks may be at least 2000 Hz. More preferably, the two resonance peaks may be within the frequency range perceivable by human ears, and the difference between the frequency values of the two resonance peaks may be at least 3000 Hz. Moreover, more preferably, the two resonance peaks may be within the frequency range perceivable by human ears, and the difference between the frequency values of the two resonance peaks may be at least 4000 Hz. One resonance peak may be within the frequency range perceivable by human ears, another one may be beyond the frequency range that a person may hear, and the difference between the frequency values of the two resonance peaks may be at least 500 Hz. Preferably, one resonance peak may be within the frequency range perceivable by human ears, another one may be beyond the frequency range that a person may hear, and the difference between the frequency values of the two resonance peaks may be at least 1000 Hz. More preferably, one resonance peak may be within the frequency range perceivable by human ears, another one may be beyond the frequency range that a person may hear, and the difference between the frequency values of the two resonance peaks may be at least 2000 Hz. More preferably, one resonance peak may be within the frequency range perceivable by human ears, another one may be beyond the frequency range that a person may hear, and the difference between the frequency values of the two resonance peaks may be at least 3000 Hz. Moreover, more preferably, one resonance peak may be within the frequency range perceivable by human ears, another one may be beyond the frequency range that a person may hear, and the difference between the frequency values of the two resonance peaks may be at least 4000 Hz. Both resonance peaks may be within the frequency range of 5 Hz-30000 Hz, and the difference between the frequency values of the two resonance peaks may be at least 400 Hz. Preferably, both resonance peaks may be within the frequency range of 5 Hz-30000 Hz, and the difference between the frequency values of the two resonance peaks may be at least 1000 Hz. More preferably, both resonance peaks may be within the frequency range of 5 Hz-30000 Hz, and the difference between the frequency values of the two resonance peaks may be at least 2000 Hz. More preferably, both resonance peaks may be within the frequency range of 5 Hz-30000 Hz, and the difference between the frequency values of the two resonance peaks may be at least 3000 Hz. Moreover, further preferably, both resonance peaks may be within the frequency range of 5 Hz-30000 Hz, and the difference between the frequency values of the two resonance peaks may be at least 4000 Hz. Both resonance peaks may be within the frequency range of 20 Hz-20000 Hz, and the difference between the frequency values of the two resonance peaks may be at least 400 Hz. Preferably, both resonance peaks may be within the frequency range of 20 Hz-20000 Hz, and the difference between the frequency values of the two resonance peaks may be at least 1000 Hz. More preferably, both resonance peaks may be within the frequency range of 20 Hz-20000 Hz, and the difference between the frequency values of the two resonance peaks may be at least 2000 Hz. More preferably, both resonance peaks may be within the frequency range of 20 Hz-20000 Hz, and the difference between the frequency values of the two resonance peaks may be at least 3000 Hz. And further preferably, both resonance peaks may be within the frequency range of 20 Hz-20000 Hz, and the difference between the frequency values of the two resonance peaks may be at least 4000 Hz. Both the two resonance peaks may be within the frequency range of 100 Hz-18000 Hz, and the difference between the frequency values of the two resonance peaks may be at least 400 Hz. Preferably, both resonance peaks may be within the frequency range of 100 Hz-18000 Hz, and the difference between the frequency values of the two resonance peaks may be at least 1000 Hz. More preferably, both resonance peaks may be within the frequency range of 100 Hz-18000 Hz, and the difference between the frequency values of the two resonance peaks may be at least 2000 Hz. More preferably, both resonance peaks may be within the frequency range of 100 Hz-18000 Hz, and the difference between the frequency values of the two resonance peaks may be at least 3000 Hz. And further preferably, both resonance peaks may be within the frequency range of 100 Hz-18000 Hz, and the difference between the frequency values of the two resonance peaks may be at least 4000 Hz. Both the two resonance peaks may be within the frequency range of 200 Hz-12000 Hz, and the difference between the frequency values of the two resonance peaks may be at least 400 Hz. Preferably, both resonance peaks may be within the frequency range of 200 Hz-12000 Hz, and the difference between the frequency values of the two resonance peaks may be at least 1000 Hz. More preferably, both resonance peaks may be within the frequency range of 200 Hz-12000 Hz, and the difference between the frequency values of the two resonance peaks may be at least 2000 Hz. More preferably, both resonance peaks may be within the frequency range of 200 Hz-12000 Hz, and the difference between the frequency values of the two resonance peaks may be at least 3000 Hz. And further preferably, both resonance peaks may be within the frequency range of 200 Hz-12000 Hz, and the difference between the frequency values of the two resonance peaks may be at least 4000 Hz. Both the two resonance peaks may be within the frequency range of 500 Hz-10000 Hz, and the difference between the frequency values of the two resonance peaks may be at least 400 Hz. Preferably, both resonance peaks may be within the frequency range of 500 Hz-10000 Hz, and the difference between the frequency values of the two resonance peaks may be at least 1000 Hz. More preferably, both resonance peaks may be within the frequency range of 500 Hz-10000 Hz, and the difference between the frequency values of the two resonance peaks may be at least 2000 Hz. More preferably, both resonance peaks may be within the frequency range of 500 Hz-10000 Hz, and the difference between the frequency values of the two resonance peaks may be at least 3000 Hz. And further preferably, both resonance peaks may be within the frequency range of 500 Hz-10000 Hz, and the difference between the frequency values of the two resonance peaks may be at least 4000 Hz. This may broaden the range of the resonance response of the speaker, thus obtaining a more ideal sound quality. It should be noted that in actual applications, there may be multiple vibration conductive plates and vibration boards to form multi-layer vibration structures corresponding to different ranges of frequency response, thus obtaining diatonic, full-ranged and high-quality vibrations of the speaker, or may make the frequency response curve meet requirements in a specific frequency range. For example, to satisfy the requirement of normal hearing, a bone conduction hearing aid may be configured to have a transducer including one or more vibration boards and vibration conductive plates with a resonance frequency in a range of 100 Hz-10000 Hz. 
     In the better implement examples, but, not limited to these examples, it is adopted that, the vibration conductive plate can be made by stainless steels, with a thickness of 0.1-0.2 mm, and when the middle three rods of the first rods group in the vibration conductive plate have a width of 0.5-1.0 mm, the low frequency resonance oscillation peak of the bone conduction speaker is located between 300 and 900 Hz. And, when the three straight rods in the second rods group have a width between 1.6 and 2.6 mm, and a thickness between 0.8 and 1.2 mm, the high frequency resonance oscillation peak of the bone conduction speaker is between 7500 and 9500 Hz. Also, the structures of the vibration conductive plate and the vibration board is not limited to three straight rods, as long as their structures can make a suitable flexibility to both vibration conductive plate and vibration board, cross-shaped rods and other rod structures are also suitable. Of course, with more compound vibration parts, more resonance oscillation peaks will be achieved, and the fitting curve will be flatter and the sound wider. Thus, in the better implement examples, more than two vibration parts, including the vibration conductive plate and vibration board as well as similar parts, overlapping each other, is also applicable, just needs more costs. 
     As shown in  FIG.  7   , in another embodiment, the compound vibration device (also referred to as “compound vibration system”) may include a vibration board  702 , a first vibration conductive plate  703 , and a second vibration conductive plate  701 . The first vibration conductive plate  703  may fix the vibration board  702  and the second vibration conductive plate  701  onto a housing  719 . The compound vibration system including the vibration board  702 , the first vibration conductive plate  703 , and the second vibration conductive plate  701  may lead to no less than two resonance peaks and a smoother frequency response curve in the range of the auditory system, thus improving the sound quality of the bone conduction speaker. The equivalent model of the compound vibration system may be shown in  FIG.  8   -A: 
     For illustration purposes,  801  represents a housing,  802  represents a panel,  803  represents a voice coil,  804  represents a magnetic circuit system,  805  represents a first vibration conductive plate,  806  represents a second vibration conductive plate, and  807  represents a vibration board. The first vibration conductive plate, the second vibration conductive plate, and the vibration board may be abstracted as components with elasticity and damping; the housing, the panel, the voice coil and the magnetic circuit system may be abstracted as equivalent mass blocks. The vibration equation of the system may be expressed as:
 
 m   6   x   6   ″+R   6 ( x   6   −x   5 )′+ k   6 ( x   6   −x   5 )= F,   (1)
 
 x   7   ″+R   7 ( x   7   −x   5 )′+ k   7 ( x   7   −x   5 )=− F,   (2)
 
 m   5   x   5   ″−R   6 ( x   6   −x   5 )′− R   7 ( x   7   −x   5 )′+ R   8   x   5   ′+k   8   x   5   −k   6 ( x   6   −x   5 )− k   7 ( x   7   −x   5 )=0,  (3)
 
wherein, F is a driving force, k 6  is an equivalent stiffness coefficient of the second vibration conductive plate, k 7  is an equivalent stiffness coefficient of the vibration board, k 8  is an equivalent stiffness coefficient of the first vibration conductive plate, R 6  is an equivalent damping of the second vibration conductive plate, R 7  is an equivalent damping of the vibration board, R 8  is an equivalent damp of the first vibration conductive plate, m 5  is a mass of the panel, m 6  is a mass of the magnetic circuit system, m 7  is a mass of the voice coil, x 5  is a displacement of the panel, x 6  is a displacement of the magnetic circuit system, x 7  is to displacement of the voice coil, and the amplitude of the panel  802  may be:
 
                       A   5     =       -       (         -     m   6       ⁢       ω   2     (       j   ⁢     R   7     ⁢   ω     -     k   7       )       +       m   7     ⁢       ω   2     (       j   ⁢     R   6     ⁢   ω     -     k   6       )         )       (             (         -     m   5       ⁢     ω   2       -       jR   8     ⁢   ω     +     k   8       )     ⁢     (         -     m   6       ⁢     ω   2       -       jR   6     ⁢   ω     +     k   6       )                 (         -     m   7       ⁢     ω   2       -       jR   7     ⁢   ω     +     k   7       )                 -     m   6       ⁢       ω   2     (         -     jR   6       ⁢   ω     +     k   6       )     ⁢     (         -     m   7       ⁢     ω   2       -       jR   7     ⁢   ω     +     k   7       )                   -     m   7       ⁢       ω   2     (         -     jR   7       ⁢   ω     +     k   7       )     ⁢     (         -     m   6       ⁢     ω   2       -       jR   6     ⁢   ω     +     k   6       )             )         ⁢     f   0         ,           (   4   )               
wherein ω is an angular frequency of the vibration, and f 0  is a unit driving force.
 
     The vibration system of the bone conduction speaker may transfer vibrations to a user via a panel (e.g., the panel  730  shown in  FIG.  7   ). According to the equation (4), the vibration efficiency may relate to the stiffness coefficients of the vibration board, the first vibration conductive plate, and the second vibration conductive plate, and the vibration damping. Preferably, the stiffness coefficient of the vibration board k 7  may be greater than the second vibration coefficient k 6 , and the stiffness coefficient of the vibration board k 7  may be greater than the first vibration factor k 8 . The number of resonance peaks generated by the compound vibration system with the first vibration conductive plate may be more than the compound vibration system without the first vibration conductive plate, preferably at least three resonance peaks. More preferably, at least one resonance peak may be beyond the range perceivable by human ears. More preferably, the resonance peaks may be within the range perceivable by human ears. More further preferably, the resonance peaks may be within the range perceivable by human ears, and the frequency peak value may be no more than 18000 Hz. More preferably, the resonance peaks may be within the range perceivable by human ears, and the frequency peak value may be within the frequency range of 100 Hz-15000 Hz. More preferably, the resonance peaks may be within the range perceivable by human ears, and the frequency peak value may be within the frequency range of 200 Hz-12000 Hz. More preferably, the resonance peaks may be within the range perceivable by human ears, and the frequency peak value may be within the frequency range of 500 Hz-11000 Hz. There may be differences between the frequency values of the resonance peaks. For example, there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks no less than 200 Hz. Preferably, there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks no less than 500 Hz. More preferably, there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks no less than 1000 Hz. More preferably, there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks no less than 2000 Hz. More preferably, there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks no less than 5000 Hz. To achieve a better effect, all of the resonance peaks may be within the range perceivable by human ears, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks no less than 500 Hz. Preferably, all of the resonance peaks may be within the range perceivable by human ears, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks no less than 1000 Hz. More preferably, all of the resonance peaks may be within the range perceivable by human ears, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks no less than 2000 Hz. More preferably, all of the resonance peaks may be within the range perceivable by human ears, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks no less than 3000 Hz. More preferably, all of the resonance peaks may be within the range perceivable by human ears, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks no less than 4000 Hz. Two of the three resonance peaks may be within the frequency range perceivable by human ears, and another one may be beyond the frequency range that a person may hear, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks no less than 500 Hz. Preferably, two of the three resonance peaks may be within the frequency range perceivable by human ears, and another one may be beyond the frequency range that a person may hear, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks no less than 1000 Hz. More preferably, two of the three resonance peaks may be within the frequency range perceivable by human ears, and another one may be beyond the frequency range that a person may hear, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks no less than 2000 Hz. More preferably, two of the three resonance peaks may be within the frequency range perceivable by human ears, and another one may be beyond the frequency range that a person may hear, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks no less than 3000 Hz. More preferably, two of the three resonance peaks may be within the frequency range perceivable by human ears, and another one may be beyond the frequency range that a person may hear, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks no less than 4000 Hz. One of the three resonance peaks may be within the frequency range perceivable by human ears, and the other two may be beyond the frequency range that a person may hear, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks no less than 500 Hz. Preferably, one of the three resonance peaks may be within the frequency range perceivable by human ears, and the other two may be beyond the frequency range that a person may hear, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks no less than 1000 Hz. More preferably, one of the three resonance peaks may be within the frequency range perceivable by human ears, and the other two may be beyond the frequency range that a person may hear, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks no less than 2000 Hz. More preferably, one of the three resonance peaks may be within the frequency range perceivable by human ears, and the other two may be beyond the frequency range that a person may hear, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks no less than 3000 Hz. More preferably, one of the three resonance peaks may be within the frequency range perceivable by human ears, and the other two may be beyond the frequency range that a person may hear, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks no less than 4000 Hz. All the resonance peaks may be within the frequency range of 5 Hz-30000 Hz, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks of at least 400 Hz. Preferably, all the resonance peaks may be within the frequency range of 5 Hz-30000 Hz, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks of at least 1000 Hz. More preferably, all the resonance peaks may be within the frequency range of 5 Hz-30000 Hz, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks of at least 2000 Hz. More preferably, all the resonance peaks may be within the frequency range of 5 Hz-30000 Hz, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks of at least 3000 Hz. And further preferably, all the resonance peaks may be within the frequency range of 5 Hz-30000 Hz, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks of at least 4000 Hz. All the resonance peaks may be within the frequency range of 20 Hz-20000 Hz, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks of at least 400 Hz. Preferably, all the resonance peaks may be within the frequency range of 20 Hz-20000 Hz, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks of at least 1000 Hz. More preferably, all the resonance peaks may be within the frequency range of 20 Hz-20000 Hz, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks of at least 2000 Hz. More preferably, all the resonance peaks may be within the frequency range of 20 Hz-20000 Hz, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks of at least 3000 Hz. And further preferably, all the resonance peaks may be within the frequency range of 20 Hz-20000 Hz, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks of at least 4000 Hz. All the resonance peaks may be within the frequency range of 100 Hz-18000 Hz, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks of at least 400 Hz. Preferably, all the resonance peaks may be within the frequency range of 100 Hz-18000 Hz, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks of at least 1000 Hz. More preferably, all the resonance peaks may be within the frequency range of 100 Hz-18000 Hz, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks of at least 2000 Hz. More preferably, all the resonance peaks may be within the frequency range of 100 Hz-18000 Hz, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks of at least 3000 Hz. And further preferably, all the resonance peaks may be within the frequency range of 100 Hz-18000 Hz, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks of at least 4000 Hz. All the resonance peaks may be within the frequency range of 200 Hz-12000 Hz, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks of at least 400 Hz. Preferably, all the resonance peaks may be within the frequency range of 200 Hz-12000 Hz, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks of at least 1000 Hz. More preferably, all the resonance peaks may be within the frequency range of 200 Hz-12000 Hz, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks of at least 2000 Hz. More preferably, all the resonance peaks may be within the frequency range of 200 Hz-12000 Hz, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks of at least 3000 Hz. And further preferably, all the resonance peaks may be within the frequency range of 200 Hz-12000 Hz, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks of at least 4000 Hz. All the resonance peaks may be within the frequency range of 500 Hz-10000 Hz, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks of at least 400 Hz. Preferably, all the resonance peaks may be within the frequency range of 500 Hz-10000 Hz, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks of at least 1000 Hz. More preferably, all the resonance peaks may be within the frequency range of 500 Hz-10000 Hz, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks of at least 2000 Hz. More preferably, all the resonance peaks may be within the frequency range of 500 Hz-10000 Hz, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks of at least 3000 Hz. Moreover, further preferably, all the resonance peaks may be within the frequency range of 500 Hz-10000 Hz, and there may be at least two resonance peaks with a difference of the frequency values between the two resonance peaks of at least 4000 Hz. In one embodiment, the compound vibration system including the vibration board, the first vibration conductive plate, and the second vibration conductive plate may generate a frequency response as shown in  FIG.  8   -B. The compound vibration system with the first vibration conductive plate may generate three obvious resonance peaks, which may improve the sensitivity of the frequency response in the low-frequency range (about 600 Hz), obtain a smoother frequency response, and improve the sound quality. 
     The resonance peak may be shifted by changing a parameter of the first vibration conductive plate, such as the size and material, so as to obtain an ideal frequency response eventually. For example, the stiffness coefficient of the first vibration conductive plate may be reduced to a designed value, causing the resonance peak to move to a designed low frequency, thus enhancing the sensitivity of the bone conduction speaker in the low frequency, and improving the quality of the sound. As shown in  FIG.  8   -C, as the stiffness coefficient of the first vibration conductive plate decreases (i.e., the first vibration conductive plate becomes softer), the resonance peak moves to the low frequency region, and the sensitivity of the frequency response of the bone conduction speaker in the low frequency region gets improved. Preferably, the first vibration conductive plate may be an elastic plate, and the elasticity may be determined based on the material, thickness, structure, or the like. The material of the first vibration conductive plate may include but not limited to steel (for example but not limited to, stainless steel, carbon steel, etc.), light alloy (for example but not limited to, aluminum, beryllium copper, magnesium alloy, titanium alloy, etc.), plastic (for example but not limited to, polyethylene, nylon blow molding, plastic, etc.). It may be a single material or a composite material that achieve the same performance. The composite material may include but not limited to reinforced material, such as glass fiber, carbon fiber, boron fiber, graphite fiber, graphene fiber, silicon carbide fiber, aramid fiber, or the like. The composite material may also be other organic and/or inorganic composite materials, such as various types of glass fiber reinforced by unsaturated polyester and epoxy, fiberglass comprising phenolic resin matrix. The thickness of the first vibration conductive plate may be not less than 0.005 mm. Preferably, the thickness may be 0.005 mm-3 mm. More preferably, the thickness may be 0.01 mm-2 mm. More preferably, the thickness may be 0.01 mm-1 mm. Moreover, further preferably, the thickness may be 0.02 mm-0.5 mm. The first vibration conductive plate may have an annular structure, preferably including at least one annular ring, preferably, including at least two annular rings. The annular ring may be a concentric ring or a non-concentric ring and may be connected to each other via at least two rods converging from the outer ring to the center of the inner ring. More preferably, there may be at least one oval ring. More preferably, there may be at least two oval rings. Different oval rings may have different curvatures radiuses, and the oval rings may be connected to each other via rods. Further preferably, there may be at least one square ring. The first vibration conductive plate may also have the shape of a plate. Preferably, a hollow pattern may be configured on the plate. Moreover, more preferably, the area of the hollow pattern may be not less than the area of the non-hollow portion. It should be noted that the above-described material, structure, or thickness may be combined in any manner to obtain different vibration conductive plates. For example, the annular vibration conductive plate may have a different thickness distribution. Preferably, the thickness of the ring may be equal to the thickness of the rod. Further preferably, the thickness of the rod may be larger than the thickness of the ring. Moreover, still, further preferably, the thickness of the inner ring may be larger than the thickness of the outer ring. 
     When the compound vibration device is applied to the bone conduction speaker, the major applicable area is bone conduction earphones. Thus the bone conduction speaker adopting the structure will be fallen into the protection of the present disclosure. 
     The bone conduction speaker and its compound vibration device stated in the present disclosure, make the technique simpler with a lower cost. Because the two parts in the compound vibration device can adjust the low frequency as well as the high frequency ranges, as shown in  FIG.  5   , which makes the achieved frequency response flatter, and voice more broader, avoiding the problem of abrupt frequency response and feeble voices caused by single vibration device, thus broaden the application prospection of bone conduction speaker. 
     In the prior art, the vibration parts did not take full account of the effects of every part to the frequency response, thus, although they could have the similar outlooks with the products described in the present disclosure, they will generate an abrupt frequency response, or feeble sound. And due to the improper matching between different parts, the resonance peak could have exceeded the human hearable range, which is between 20 Hz and 20 KHz. Thus, only one sharp resonance peak as shown in  FIG.  4    appears, which means a pretty poor tone quality. 
     It should be made clear that, the above detailed description of the better implement examples should not be considered as the limitations to the present disclosure protections. The extent of the patent protection of the present disclosure should be determined by the terms of claims. 
     EXAMPLES 
     Example 1 
     A bone conduction speaker may include a U-shaped headset bracket/headset lanyard, two vibration units, a transducer connected to each vibration unit. The vibration unit may include a contact surface and a housing. The contact surface may be an outer surface of a silicone rubber transfer layer and may be configured to have a gradient structure including a convex portion. A clamping force between the contact surface and skin due to the headset bracket/headset lanyard may be unevenly distributed on the contact surface. The sound transfer efficiency of the portion of the gradient structure may be different from the portion without the gradient structure. 
     Example 2 
     This example may be different from Example 1 in the following aspects. The headset bracket/headset lanyard as described may include a memory alloy. The headset bracket/headset lanyard may match the curves of different users&#39; heads and have a good elasticity and a better wearing comfort. The headset bracket/headset lanyard may recover to its original shape from a deformed status last for a certain period. As used herein, the certain period may refer to ten minutes, thirty minutes, one hour, two hours, five hours, or may also refer to one day, two days, ten days, one month, one year, or a longer period. The clamping force that the headset bracket/headset lanyard provides may keep stable, and may not decline gradually over time. The force intensity between the bone conduction speaker and the body surface of a user may be within an appropriate range, so as to avoid pain or clear vibration sense caused by undue force when the user wears the bone conduction speaker. Moreover, the clamping force of bone conduction speaker may be within a range of 0.2 N˜1.5 N when the bone conduction speaker is used. 
     Example 3 
     The difference between this example and the two examples mentioned above may include the following aspects. The elastic coefficient of the headset bracket/headset lanyard may be kept in a specific range, which results in the value of the frequency response curve in low frequency (e.g., under 500 Hz) being higher than the value of the frequency response curve in high frequency (e.g., above 4000 Hz). 
     Example 4 
     The difference between Example 4 and Example 1 may include the following aspects. The bone conduction speaker may be mounted on an eyeglass frame, or in a helmet or mask with a special function. 
     Example 5 
     The difference between this example and Example 1 may include the following aspects. The vibration unit may include two or more panels, and the different panels or the vibration transfer layers connected to the different panels may have different gradient structures on a contact surface being in contact with a user. For example, one contact surface may have a convex portion, the other one may have a concave structure, or the gradient structures on both the two contact surfaces may be convex portions or concave structures, but there may be at least one difference between the shape or the number of the convex portions. 
     Example 6 
     A portable bone conduction hearing aid may include multiple frequency response curves. A user or a tester may choose a proper response curve for hearing compensation according to an actual response curve of the auditory system of a person. In addition, according to an actual requirement, a vibration unit in the bone conduction hearing aid may enable the bone conduction hearing aid to generate an ideal frequency response in a specific frequency range, such as 500 Hz-4000 Hz. 
     Example 7 
     A vibration generation portion of a bone conduction speaker may be shown in  FIG.  9   -A. A transducer of the bone conduction speaker may include a magnetic circuit system including a magnetic flux conduction plate  910 , a magnet  911  and a magnetizer  912 , a vibration board  914 , a coil  915 , a first vibration conductive plate  916 , and a second vibration conductive plate  917 . The panel  913  may protrude out of the housing  919  and may be connected to the vibration board  914  by glue. The transducer may be fixed to the housing  919  via the first vibration conductive plate  916  forming a suspended structure. 
     A compound vibration system including the vibration board  914 , the first vibration conductive plate  916 , and the second vibration conductive plate  917  may generate a smoother frequency response curve, so as to improve the sound quality of the bone conduction speaker. The transducer may be fixed to the housing  919  via the first vibration conductive plate  916  to reduce the vibration that the transducer is transferring to the housing, thus effectively decreasing sound leakage caused by the vibration of the housing, and reducing the effect of the vibration of the housing on the sound quality.  FIG.  9   -B shows frequency response curves of the vibration intensities of the housing of the vibration generation portion and the panel. The bold line refers to the frequency response of the vibration generation portion including the first vibration conductive plate  916 , and the thin line refers to the frequency response of the vibration generation portion without the first vibration conductive plate  916 . As shown in  FIG.  9   -B, the vibration intensity of the housing of the bone conduction speaker without the first vibration conductive plate may be larger than that of the bone conduction speaker with the first vibration conductive plate when the frequency is higher than 500 Hz.  FIG.  9   -C shows a comparison of the sound leakage between a bone conduction speaker includes the first vibration conductive plate  916  and another bone conduction speaker does not include the first vibration conductive plate  916 . The sound leakage when the bone conduction speaker includes the first vibration conductive plate may be smaller than the sound leakage when the bone conduction speaker does not include the first vibration conductive plate in the intermediate frequency range (for example, about 1000 Hz). It can be concluded that the use of the first vibration conductive plate between the panel and the housing may effectively reduce the vibration of the housing, thereby reducing the sound leakage. 
     The first vibration conductive plate may be made of the material, for example but not limited to stainless steel, copper, plastic, polycarbonate, or the like, and the thickness may be in a range of 0.01 mm-1 mm. 
     Example 8 
     This example may be different with Example 7 in the following aspects. As shown in  FIG.  10   , the panel  1013  may be configured to have a vibration transfer layer  1020  (for example but not limited to, silicone rubber) to produce a certain deformation to match a user&#39;s skin. A contact portion being in contact with the panel  1013  on the vibration transfer layer  1020  may be higher than a portion not being in contact with the panel  1013  on the vibration transfer layer  1020  to form a step structure. The portion not being in contact with the panel  1013  on the vibration transfer layer  1020  may be configured to have one or more holes  1021 . The holes on the vibration transfer layer may reduce the sound leakage: the connection between the panel  1013  and the housing  1019  via the vibration transfer layer  1020  may be weakened, and vibration transferred from panel  1013  to the housing  1019  via the vibration transfer layer  1020  may be reduced, thereby reducing the sound leakage caused by the vibration of the housing; the area of the vibration transfer layer  1020  configured to have holes on the portion without protrusion may be reduced, thereby reducing air and sound leakage caused by the vibration of the air; the vibration of air in the housing may be guided out, interfering with the vibration of air caused by the housing  1019 , thereby reducing the sound leakage. 
     Example 9 
     The difference between this example and Example 7 may include the following aspects. As the panel may protrude out of the housing, meanwhile, the panel may be connected to the housing via the first vibration conductive plate, the degree of coupling between the panel and the housing may be dramatically reduced, and the panel may be in contact with a user with a higher freedom to adapt complex contact surfaces (as shown in the right figure of  FIG.  11   -A) as the first vibration conductive plate provides a certain amount of deformation. The first vibration conductive plate may incline the panel relative to the housing with a certain angle. Preferably, the slope angle may not exceed 5 degrees. 
     The vibration efficiency may differ with contacting statuses. A better contacting status may lead to a higher vibration transfer efficiency. As shown in  FIG.  11   -B, the bold line shows the vibration transfer efficiency with a better contacting status, and the thin line shows a worse contacting status. It may be concluded that the better contacting status may correspond to a higher vibration transfer efficiency. 
     Example 10 
     The difference between this example and Example 7 may include the following aspects. A boarder may be added to surround the housing. When the housing contact with a user&#39;s skin, the surrounding boarder may facilitate an even distribution of an applied force, and improve the user&#39;s wearing comfort. As shown in  FIG.  12   , there may be a height difference do between the surrounding border  1210  and the panel  1213 . The force from the skin to the panel  1213  may decrease the distanced between the panel  1213  and the surrounding border  1210 . When the force between the bone conduction speaker and the user is larger than the force applied to the first vibration conductive plate with a deformation of do, the extra force may be transferred to the user&#39;s skin via the surrounding border  1210 , without influencing the clamping force of the vibration portion, with the consistency of the clamping force improved, thereby ensuring the sound quality. 
     Example 11 
     The difference between this example and Example 8 may include the following aspects. As shown in  FIG.  13   , sound guiding holes are located at the vibration transfer layer  1320  and the housing  1319 , respectively. The acoustic wave formed by the vibration of the air in the housing is guided to the outside of the housing, and interferes with the leaked acoustic wave due to the vibration of the air out of the housing, thus reducing the sound leakage. 
     It should be noted that the bone conduction speakers described above are only for illustration purposes, other acoustic output apparatus may have different structures. For example, an acoustic output apparatus may include a Bluetooth low energy (BLE) module configured to establish communication between the acoustic output apparatus and a terminal device of a user. As another example, the acoustic output apparatus may include at least one earphone core (e.g., an earphone core  1510 ) including at least one acoustic driver (e.g., the vibration device as described in  FIGS.  1 - 13   ) for outputting sound through one or more sound guiding holes (e.g., sound guiding holes  1411  as described in  FIG.  14   ) set on the acoustic output apparatus. As still another example, the acoustic output apparatus may include one or more sensors, a controller, a power source assembly, and a flexible circuit board. The one or more sensors may be configured to detect the status information of a user of the acoustic output apparatus. The controller may be configured to cause the vibration device to output sound based on the detected status information of the user. The power source assembly may be configured to provide electrical power to the at least earphone core (e.g., the vibration device thereof), the one or more sensors, and the controller. The flexible circuit board may be configured to connect the at least earphone core (e.g., the vibration device thereof) and the power source assembly. The BLE module may be integrated on a same circuit board with the controller and the at least earphone core. The circuit board may be connected to the power source assembly through the flexible circuit board. More descriptions regarding the acoustic output apparatus may be found elsewhere in the present disclosure (e.g.,  FIGS.  14 - 18    and relevant descriptions thereof). 
       FIG.  14    is a schematic diagram illustrating an exemplary acoustic output apparatus embodied as glasses according to some embodiments of the present disclosure. As shown in  FIG.  14   , the glasses  1400  may include a frame and lenses  1440 . The frame may include legs  1410  and  1420 , a lens ring  1430 , a nose pad  1450 , or the like. The legs  1410  and  1420  may be used to support the lens ring  1430  and the lenses  1440 , and fix the glasses  1400  on the user&#39;s face. The lens ring  1430  may be used to support the lenses  1440 . The nose pad  1450  may be used to fix the glasses  1400  on the user&#39;s nose. 
     The glasses  1400  may be provided with a plurality of components which may implement different functions. Exemplary components may include a power source assembly for providing power, an acoustic driver for generating sound, a microphone for detecting external sound, a bluetooth module for connecting the glasses  1400  to other devices, a controller for controlling the operation of other components, or the like, or any combination thereof. In some embodiments, the interior of the leg  1410  and/or the leg  1420  may be provided as a hollow structure for accommodating the one or more components. 
     The glasses  1400  may be provided with a plurality of hollow structures. For example, as shown in  FIG.  14   , a side of the leg  1410  and/or the leg  1420  facing away from the user&#39;s face may be provided with sound guiding holes  1411 . The sound guiding holes  1411  may be connected to one or more acoustic drivers that are set inside of the glasses  1400  to export sound produced by the one or more the acoustic drivers. In some embodiments, the sound guiding holes  1411  may be provided at a position near the user&#39;s ear on the leg  1410  and/or the leg  1420 . For example, the sound guiding holes  1411  may be provided at a rear end of the leg  1410  and/or the leg  1420  being far away from the lens ring  1430 , a bending part  1460  of the leg, or the like. As another example, the glasses  1400  may also have a power interface  1412 , which may be used to charge the power source assembly in the glasses  1400 . The power interface  1412  may be provided on a side of the leg  1410  and/or the leg  1420  facing the user&#39;s face. Exemplary power interfaces may include a dock charging interface, a DC charging interface, a USB charging interface, a lightning charging interface, a wireless charging interface, a magnetic charging interface, or the like, or any combination thereof. In some embodiments, one or more sound inlet holes  1413  may also be provided on the glasses  1400 , and may be used to transmit external sounds (for example, a user&#39;s voice, ambient sound, etc.) to the microphones in the glasses  1400 . The sound inlet holes  1413  may be provided at a position facilitating an acquisition of the user&#39;s voice on the glasses  1400 , for example, a position near the user&#39;s mouth on the leg  1410  and/or  1420 , a position near the user&#39;s mouth under the lens ring  1430 , a position on the nose pad  1450 , or any combination thereof. In some embodiments, shapes, sizes, and counts of the one or more hollow structures on the glasses  1400  may vary according to actual needs. For example, the shapes of the hollow structures may include, but not limited to, a square shape, a rectangle shape, a triangle shape, a polygon shape, a circle shape, an ellipse shape, an irregular shape, or the like. 
     In some embodiments, the glasses  1400  may be further provided with one or more button structures, which may be used to implement interact ions between the user and the glasses  1400 . As shown in  FIG.  14   , the one or more button structures may include a power button  1421 , a sound adjustment button  1422 , a playback control button  1423 , a bluetooth button  1424 , or the like. The power button  1421  may include a power on button, a power off button, a power hibernation button, or the like, or any combination thereof. The sound adjustment button  1422  may include a sound increase button, a sound decrease button, or the like, or any combination thereof. The playback control button  1423  may include a playback button, a pause button, a resume playback button, a call playback button, a call drop button, a call hold button, or the like, or any combination thereof. The bluetooth button  1424  may include a bluetooth connection button, a bluetooth off button, a selection button, or the like, or any combination thereof. In some embodiments, the button structures may be provided on the glasses  1400 . For example, the power button may be provided on the leg  1410 , the leg  1420 , or the lens ring  1430 . In some embodiments, the one or more button structures may be provided in one or more control devices. The glasses  1400  may be connected to the one or more control devices via a wired or wireless connection. The control devices may transmit instructions input by the user to the glasses  1400 , so as to control the operations of the one or more components in the glasses  1400 . 
     In some embodiments, the glasses  1400  may also include one or more indicators to indicate information of one or more components in the glasses  1400 . For example, the indicators may be used to indicate a power status, a bluetooth connection status, a playback status, or the like, or any combination thereof. In some embodiments, the indicators may indicate related information of the components via different indicating conditions (for example, different colors, different time, etc.). Merely by way of example, when a power indicator is red, it is indicated that the power source assembly may be in a state of low power. When the power indicator is green, indicating that the power source assembly may be a state of full power. As another example, a bluetooth indicator may flash intermittently, indicating that the bluetooth is connecting to another device. The bluetooth indicator may be blue, indicating that the bluetooth may be connected successfully. 
     In some embodiments, a sheath may be provided on the leg  1410  and/or the leg  1420 . The sheath may be made of soft material with a certain elasticity, such as silicone, rubber, etc., so as to provide a better sense of touch for the user. 
     In some embodiments, the frame may be formed integrally, or assembled by plugging, inserting, or the like. In some embodiments, materials used to manufacture the frame may include but not limited to, steel, alloy, plastic, or other single or composite materials. The steel may include but not limited to, stainless steel, carbon steel, or the like. The alloy may include but is not limited to, aluminum alloy, chromium-molybdenum steel, rhenium alloy, magnesium alloy, titanium alloy, magnesium-lithium alloy, nickel alloy, or the like. The plastic may include but not limited to, acrylonitrile-butadiene-styrene copolymer (Acrylonitrile butadiene styrene, ABS), polystyrene (PS), high impact polystyrene (HIPS), polypropylene (PP), polyethylene terephthalate (PET), polyester (PES), polycarbonate (PC), polyamide (PA), polyvinyl chloride (PVC), polyethylene and blown nylon, or the like. The single or composite materials may include but not limited to, glass fiber, carbon fiber, boron fiber, graphite fiber, graphene fiber, silicon carbide fiber, aramid fiber and other reinforcing materials; or a composite of other organic and/or inorganic materials, such as glass fiber reinforced unsaturated polyester, various types of glass steel with epoxy resin or phenolic resin, etc. 
     The description of the glasses  1400  may be provided for illustration purposes and not intended to limit the scope of the present disclosure. For those skilled in the art, various changes and modifications may be made according to the description of the present disclosure. For example, the glasses  1400  may include one or more cameras to capture environmental information (for example, scenes in front of the user). As another example, the glasses  1400  may also include one or more projectors for projecting pictures (for example, pictures that users see through the glasses  1400 ) onto a display screen. 
       FIG.  15    is a schematic diagram illustrating components in an acoustic output apparatus (e.g., the glasses  1400 ). As shown in  FIG.  15   , the acoustic output apparatus  200  may include one or more of an earphone core  1510 , an auxiliary function module  1520 , a flexible circuit board  1530 , a power source assembly  1540 , a controller  1550 , or the like. 
     The earphone core  1510  may be configured to process signals containing audio information, and convert the signals into sound signals. The audio information may include video or audio files with a specific data format, or data or files that may be converted into sound in a specific manner. The signals containing the audio information may include electrical signals, optical signals, magnetic signals, mechanical signals or the like, or any combination thereof. The processing operation may include frequency division, filtering, denoising, amplification, smoothing, or the like, or any combination thereof. The conversion may involve a coexistence and interconversion of energy of different types. For example, the electrical signal may be converted into mechanical vibrations that generates sound through the earphone core  1510  directly. As another example, the audio information may be included in the optical signal, and a specific earphone core may implement a process of converting the optical signal into a vibration signal. Energy of other types that may coexist and interconvert to each other during the working process of the earphone core  1510  may include thermal energy, magnetic field energy, and so on. 
     In some embodiments, the earphone core  1510  may include one or more acoustic drivers. The acoustic driver(s) may be used to convert electrical signals into sound for playback. 
     The auxiliary function module  1520  may be configured to receive auxiliary signals and execute auxiliary functions. The auxiliary function module  1520  may include one or more microphones, key switches, bluetooth modules, sensors, or the like, or any combination thereof. The auxiliary signals may include status signals (for example, on, off, hibernation, connection, etc.) of the auxiliary function module  1520 , signals generated through user operations (for example, input and output signals generated by the user through keys, voice input, etc.), signals in the environment (for example, audio signals in the environment), or the like, or any combination thereof. In some embodiments, the auxiliary function module  1520  may transmit the received auxiliary signals through the flexible circuit board  1530  to the other components in the acoustic output apparatus  1500  for processing. 
     A button module may be configured to control the acoustic output apparatus  1500 , so as to implement the interaction between the user and the acoustic output apparatus  1500 . The user may send a command to the acoustic output apparatus  1500  through the button module to control the operation of the acoustic output apparatus  1500 . In some embodiments, the button module may include a power button, a playback control button, a sound adjustment button, a telephone control button, a recording button, a noise reduction button, a bluetooth button, a return button, or the like, or any combination thereof. The power button may be configured to control the status (on, off, hibernation, or the like) of the power source assembly module. The playback control button may be configured to control sound playback by the earphone core  1510 , for example, playing information, pausing information, continuing to play information, playing a previous item, playing a next item, mode selection (e.g. a sport mode, a working mode, an entertainment mode, a stereo mode, a folk mode, a rock mode, a bass mode, etc.), playing environment selection (e.g., indoor, outdoor, etc.), or the like, or any combination thereof. The sound adjustment button may be configured to control a sound amplitude of the earphone core  1510 , for example, increasing the sound, decreasing the sound, or the like. The telephone control button may be configured to control telephone answering, rejection, hanging up, dialing back, holding, and/or recording incoming calls. The record button may be configured to record and store the audio information. The noise reduction button may be configured to select a degree of noise reduction. For example, the user may select a level or degree of noise reduction manually, or the acoustic output apparatus  1500  may select a level or degree of noise reduction automatically according to a playback mode selected by the user or detected ambient sound. The bluetooth button may be configured to turn on bluetooth, turn off bluetooth, match bluetooth, connect bluetooth, or the like, or any combination thereof. The return button may be configured to return to a previous menu, interface, or the like. 
     A sensor may be configured to detect information related to the acoustic output apparatus  1500  and/or status information of a user of the acoustic output apparatus  1500 . For example, the sensor may be configured to detect the user&#39;s fingerprint, and transmit the detected fingerprint to the controller  1550 . The controller  1550  may match the received fingerprint with a fingerprint pre-stored in the acoustic output apparatus  1500 . If the matching is successful, the controller  1550  may generate an instruction that may be transmitted to each component to initiate the sound output apparatus  1500 . As another example, the sensor may be configured to detect the position of the acoustic output apparatus  1500 . When the sensor detects that the acoustic output apparatus  1500  is detached from a user&#39;s face, the sensor may transmit the detected information to the controller  1550 , and the controller  1550  may generate an instruction to pause or stop the playback of the acoustic output apparatus  1500 . In some embodiments, exemplary sensors may include a ranging sensor (e.g., an infrared ranging sensor, a laser ranging sensor, etc.), a speed sensor, a gyroscope, an accelerometer, a positioning sensor, a displacement sensor, a pressure sensor, a gas sensor, a light sensor, a temperature sensor, a humidity sensor, a fingerprint sensor, an image sensor, an iris sensor, an image sensor (e.g., a vidicon, a camera, etc.), or the like, or any combination thereof. 
     The flexible circuit board  1530  may be configured to connect different components in the acoustic output apparatus  1500 . The flexible circuit board  1530  may be a flexible printed circuit (FPC). In some embodiments, the flexible circuit board  1530  may include one or more bonding pads and/or one or more flexible wires. The one or more bonding pads may be configured to connect the one or more components of the acoustic output apparatus  1500  or other bonding pads. One or more leads may be configured to connect the components of the acoustic output apparatus  1500  with one bonding pad, two or more bonding pads, or the like. In some embodiments, the flexible circuit board  1530  may include one or more flexible circuit boards. Merely by ways of example, the flexible circuit board  1530  may include a first flexible circuit board and a second flexible circuit board. The first flexible circuit board may be configured to connect two or more of the microphone, the earphone core  1510 , and the controller  1550 . The second flexible circuit board may be configured to connect two or more of the power source assembly  1540 , the earphone core  1510 , the controller  1550 , or the like. In some embodiments, the flexible circuit board  1530  may be an integral structure including one or more regions. For example, the flexible circuit board  1530  may include a first region and a second region. The first region may be provided with flexible leads for connecting the bonding pads on the flexible circuit board  1530  and other components on the acoustic output apparatus  1500 . The second region may be configured to set one or more bonding pads. In some embodiments, the power source assembly  1540  and/or the auxiliary function module  1520  may be connected to the flexible circuit board  1530  (for example, the bonding pads) through the flexible leads of the flexible circuit board  1530 . 
     The power source assembly  1540  may be configured to provide electrical power to the components of the acoustic output apparatus  1500 . In some embodiments, the power source assembly  1540  may include a flexible circuit board, a battery, etc. The flexible circuit board may be configured to connect the battery and other components of the acoustic output apparatus  1500  (for example, the earphone core  1510 ), and provide power for operations of the other components. In some embodiments, the power source assembly  1540  may also transmit its state information to the controller  1550  and receive instructions from the controller  1550  to perform corresponding operations. The state information of the power source assembly  1540  may include an on/off state, state of charge, time for use, a charging time, or the like, or any combination thereof. In some embodiments, the power source assembly may include a body region and a sealing region. The thickness of the body region may be greater than the thickness of the sealing region. A side surface of the sealing region and a side surface of the body region may have a shape of a stair. 
     According to information of the one or more components of the acoustic output apparatus  1500 , the controller  1550  may generate an instruction to control the power source assembly  1540 . For example, the controller  1550  may generate control instructions to control the power source assembly  1540  to provide power to the earphone core  1510  for generating sound. As another example, when the acoustic output apparatus  1500  does not receive input information within a certain time, the controller  1550  may generate a control instruction to control the power source assembly  1540  to enter a hibernation state. In some embodiments, the power source assembly  1540  may include a storage battery, a dry battery, a lithium battery, a Daniel battery, a fuel battery, or any combination thereof. 
     Merely by way of example, the controller  1550  may receive a sound signal from the user, for example, “play a song”, from the auxiliary function module  1520 . By processing the sound signal, the controller  1550  may generate control instructions related to the sound signal. For example, the control instructions may control the earphone core  1510  to obtain information of songs from the storage module (or other devices). Then an electric signal for controlling the vibration of the earphone core  1510  may be generated according to the information. 
     In some embodiments, the controller  1550  may include one or more electronic frequency division modules. The electronic frequency division modules may divide a frequency of a source signal. The source signal may come from one or more sound source apparatus (for example, a memory storing audio data) integrated in the acoustic output apparatus. The source signal may also be an audio signal (for example, an audio signal received from the auxiliary function module  1520 ) received by the acoustic output apparatus  1500  in a wired or wireless manner. In some embodiments, the electronic frequency division modules may decompose an input source signal into two or more frequency-divided signals containing different frequencies. For example, the electronic frequency division module may decompose the source signal into a first frequency-divided signal with high-frequency sound and a second frequency-divided signal with low-frequency sound. Signals processed by the electronic frequency division modules may be transmitted to the acoustic driver in the earphone core  1510  in a wired or wireless manner. 
     In some embodiments, the controller  1550  may include a central processing unit (CPU), an application-specific integrated circuit (ASIC), an application-specific instruction-set processor (ASIP), a graphics processing unit (GPU), a physical processing unit (PPU), a digital signal processor (DSP), a field-programmable gate array (FPGA), a programmable logic device (PLD), a controller, a microcontroller unit, a reduced instruction set computer (RISC), a microprocessor, or the like, or any combination thereof. 
     In some embodiments, one or more of the earphone core  1510 , the auxiliary function module  1520 , the flexible circuit board  1530 , the power source assembly  1530 , and the controller  1550  may be provided in the frame of the glasses  1400 . Specifically, one or more of the electronic components may be provided in the hollow structure of the leg  1410  and/or the leg  1420 . The connection and/or communication between the electronic components provided in the leg  1410  and/or the leg  1420  may be wired or wireless. The wired connection may include metal cables, fiber optical cables, hybrid cables, or the like, or any combination thereof. The wireless connection may include a local area network (LAN), a wide area network (WAN), a bluetooth, a ZigBee, a near field communication (NFC), or the like, or any combination thereof. 
     The description of the acoustic output apparatus  1500  may be for illustration purposes, and not intended to limit the scope of the present disclosure. For those skilled in the art, various changes and modifications may be made according to the description of the present disclosure. For example, the components and/or functions of the acoustic output apparatus  1500  may be changed or modified according to a specific implementation. For example, the acoustic output apparatus  1500  may include a storage component for storing signals containing audio information. As another example, the acoustic output apparatus  1500  may include one or more processors, which may execute one or more sound signal processing algorithms for processing sound signals. These changes and modifications may remain within the scope of the present disclosure. 
       FIG.  16    is a schematic diagram illustrating a bluetooth low energy (BLE) module according to some embodiments of the present disclosure. In some embodiments, the acoustic output apparatus (e.g., the glasses  1400 ) may further include a BLE module  1600 . For example, the bluetooth modules used in the glasses  100  may be implemented by the BLE module. The BLE module  1600  may include a processor  1610 , a storage  1620 , a transceiver  1630 , and an interface  1640 . 
     The BLE module  1600  may facilitate communications between components of the acoustic output apparatus (e.g., one or more sensors such as a locating sensor, an orientation sensor, an inertial sensor, etc.) or the acoustic output apparatus and an external device (e.g., a terminal device of a user, a cloud data center, a peripheral device of the acoustic output apparatus, etc.) using BLE technology. The locating sensor may determine a geographic location of the acoustic output apparatus, for example, based on one or more location-based detection systems such as a global positioning system (GPS), a Wi-Fi location system, an infra-red (IR) location system, a bluetooth beacon system, etc. The orientation sensor may track an orientation of the user and/or the acoustic output apparatus. The orientation sensor may include a head-tracking device and/or a torso-tracking device for detecting a direction in which the user is facing, as well as the movement of the user and/or the acoustic output apparatus. The inertial sensor may sense gestures of the user or a body part (e.g., head, torso, limbs) of the user. The inertial sensor may include an accelerometer, a gyroscope, a magnetometer, or the like, or any combination thereof. BLE is a wireless communication technology published by the Bluetooth Special Interest Group (BT-SIG) standard as a component of Bluetooth Core Specification Version 4.0. BLE is a lower power, lower complexity, and lower cost wireless communication protocol, designed for applications requiring lower data rates and shorter duty cycles. Inheriting the protocol stack and star topology of classical Bluetooth, BLE redefines the physical layer specification, and involves new features such as a very-low power idle mode, a simple device discovery, and short data packets, etc. 
     The transceiver  1630  may receive data (e.g., an audio message) to be played by the acoustic output apparatus. The transceiver  1630  may include any suitable logic and/or circuitry to facilitate receiving signals from and/or transmitting signals to other components of the acoustic output apparatus or an external device wirelessly. In some embodiments, the transceiver  1630  may transmit the received data to the processor  1610  for processing. For example, the processor  1610  may perform a noise reduction on the received data. As another example, the processor  1610  may serve as an equalizer, which adjusts the volume, the tone, etc. of an audio message adaptively according to actual needs. In some embodiments, the processor  1610  may execute instructions embodied in software (including firmware) associated with the operations of BLE module  1600  for managing the operations of transceiver  1630 . In some embodiments, the processor  1610  may facilitate processing and forwarding of received data from the transceiver  1630  and/or processing and forwarding of data to be transmitted by the transceiver  1630 . The storage  1620  may store one or more instructions executed by the processor  1610 , dated received from the transceiver  1630  and/or data to be transmitted by the transceiver  1630 , or the like. The storage  1620  may include but is not limited to, RAM, ROM, flash memory, a hard drive, a solid state drive, or other volatile and/or non-volatile storage devices. The BLE module  1600  may interact with one or more modules or components of the acoustic output apparatus via the interface  1640 . 
     It will be appreciated that, in some embodiments, the functionality of one or more of the processor  1610 , the storage  1620 , the transceiver  1630 , and/or the interface  1640  may be integrated with one or more modules of the acoustic output apparatus on a same circuit board, such as a system on a chip (SOC), an application specific integrated circuit (ASIC), etc. In some embodiments, the BLE module  1600  or one or more components thereof may be integrated on a same circuit board with the earphone core  1510  and/or the controller  1550 . The circuit board may connect to the power source assembly through the flexible circuit board  1530 . 
       FIG.  17    is a flow chart illustrating an exemplary process for transmitting audio data to a terminal device through the BLE module according to some embodiments of the present disclosure. 
     In  1710 , audio data may be encoded. In some embodiments, the acoustic output apparatus may transmit audio data to a terminal device (e.g., a loudspeaker, a mobile phone, etc.) through the BLE module  1600 . The BLE module  1600  may encode the audio data to be transmitted. In some embodiments, the BLE module  1600  may encode the audio data using a Low Complexity Communications Codec (LC3). 
     In  1720 , a BLE data packet may be generated. A BLE data packet may be generated based on encoded audio data. In some embodiments, the BLE module  1600  may obtain parameters or attributes associated with the audio data before the BLE data packets are generated. The parameters or attributes associated with the audio data may include parameters for decoding the audio data (e.g., the codec of the audio data), parameters for demodulating the audio data, the volume of the audio data, the tone of the audio data, the content of the audio data, or the like, or any combination thereof. In some embodiments, the BLE data packets may also include the parameters or attributes associated with the audio data. In some embodiments, the audio data may be divided into multiple data segments of particular sizes if the audio data is oversized. A BLE data packet may be generated based on each data segment such that the transmission speed of the audio data may be improved. 
     In  1730 , the BLE data packet may be modulated onto a BLE channel. In some embodiments, if the audio data is divided into multiple data segments, multiple BLE channels may be established, and each of the multiple data segments may be modulated onto a BLE channel. 
     In  1740 , the modulated BLE data packet may be transmitted to a terminal device through the BLE channel. In some embodiments, data transmission between the BLE module  1600  and the terminal device may be implemented according to a protocol suitable for BLE (e.g., LE audio). After the terminal device receives the audio data, the playback of the audio data on the terminal device may be realized according to the parameters or attributes associated with the audio data. 
       FIG.  18    is a flow chart illustrating an exemplary process for determining a location of the acoustic output apparatus using the BLE module according to some embodiments of the present disclosure. 
     In some embodiments, the BLE module may determine a location of the acoustic output apparatus. The BLE module may function as the locating sensor. In some embodiments, the locating sensor may be omitted in the acoustic output apparatus, thus reducing the size, the weight, and the power consumption of the acoustic output apparatus. In some embodiments, the BLE module may determine the location of the acoustic output apparatus by performing the operations  1810  through  1840  in the process  1800 . 
     In  1810 , position tags around the acoustic output apparatus may be scanned. In some embodiments, a position tag refers to an identifier indicating a position of a BLE device. In some embodiments, the identifier may include a character string representing the position of the BLE device. In some embodiments, the identifier may further include character strings representing a name, a service, a device ID, etc., of the BLE device. In some embodiment, the BLE device may be a BLE transceiver set at a virtual or physical location. In some embodiments, the BLE device may be another BLE module implemented in a terminal device (e.g., a mobile phone, a smart wearable device, etc.) of a user. In some embodiments, the BLE module  1600  may scan for position tags in a certain range (for example, in a circular range centered by the acoustic output apparatus with a radius of 100 meters). In some embodiments, the manner in which the scanning operation is performed, a frequency of scanning operation, and a width of a scanning window (e.g., the certain range) of the scanning operation may be set by a user (e.g., a wearer of the acoustic output apparatus), according to default settings of the acoustic output apparatus, etc. Within the scanning window, the BLE module  1600  may detect position tags of multiple BLE devices sensed by the transceiver  1630 . 
     In  1820 , messages related to one or more detected position tags may be obtained within the scanning window. In some embodiments, the BLE module  1600  may detect multiple position tags, and obtain messages including identifiers from BLE devices corresponding to the multiple position tags. In some embodiments, the processor  1610  of the BLE module  1600  may determine if the messages are obtained from “allowed” BLE devices (e.g., qualified BLE transceivers). The BLE module  1600  may determine a value of an identifier contained in each message. In some embodiments, a value of an identifier contained in a message may be determined based on at least one of character strings of the position, the name, the service, the device ID, etc. of the identifier. The processor  1610  of the BLE module  1600  may compare the value with one or more preset values. In some embodiments, the BLE module  1600  may identify the one or more position tags and corresponding “allowed” BLE devices according to the comparison. In some embodiments, in order to provide a relatively precise position of the acoustic output apparatus, at least three position tags may be obtained within the scanning window. 
     In  1830 , one or more parameters associated with the messages may be determined. When the BLE module  1600  confirms that the messages are obtained from the “allowed” BLE devices, the processor  1610  may instruct the BLE module  1600  to record a radio parameter associated with each message. In some embodiments, the radio parameter may include a received signal strength indicator (RSSI) value, a bit error rate (BER), etc. In some embodiments, the message, the radio parameter regarding the message, and the identifier obtained from the message may be stored in the storage  1620 . 
     In  1840 , the location of the acoustic output apparatus may be calculated based on the obtained messages and the one or more parameters associated with the messages. In some embodiments, the processor  1610  may calculate a relative location of the acoustic output apparatus relative to the “allowed” BLE devices from which the one or more position tags are obtained based on the messages and the one or more parameters associated with the messages. Since locations of the “allowed” BLE devices are known, the location of the acoustic output apparatus (e.g., in forms of coordinates of latitude and longitude) may be determined based on the relative location of the acoustic output apparatus relative to the “allowed” BLE devices. The determination of the location of the acoustic output apparatus may be performed using any suitable methods. In this way, the calculation of the location of the acoustic output apparatus may use less battery power. In some embodiments, if there are more than three position tags are detected, and messages related to the position tags are obtained, the processor  1610  may rank the messages according to the RSSI values associated with the messages. Messages corresponding to three highest RSSI values may be identified from the more than three messages, and the identified messages and the one or more parameters associated with the messages may be used to determine the location of the acoustic output apparatus. 
     In some embodiments, the location of the acoustic output apparatus may be determined at any suitable frequency. Determined locations of the acoustic output apparatus may be filtered in any suitable manner so as to minimize errors due to external factors, such as a person standing between the acoustic output apparatus and the “allowed” BLE devices. 
     The embodiments described above are merely implements of the present disclosure, and the descriptions may be specific and detailed, but these descriptions may not limit the present disclosure. It should be noted that those skilled in the art, without deviating from concepts of the bone conduction speaker, may make various modifications and changes to, for example, the sound transfer approaches described in the specification, but these combinations and modifications are still within the scope of the present disclosure.