CN1135058C - Acoustic device according to bending wave principle - Google Patents

Abstract

An acoustic device has an outer shell(1)supporting bending waves and enclosing a volume(2). The bending waves couple to the enclosed volume to provide coupled resonant modes. A transducer(3, 5)is coupled to the shell to excite the coupled resonant modes. The coupling of the enclosed volume can improve the distribution of resonant modes.

Description

Acoustics and driving method thereof according to bending wave principle

FIELD OF THE INVENTION

The present invention relates to acoustics and driving method thereof, its pattern is the element of use support bending wave action on its whole surface, around bending wave is coupled to again.This device can be used as loud speaker or microphone.

The background of invention

International Patent Application WO 97/09842 reaches relevant application case, has described to have loud speaker and other acoustics that an audio element and is coupled to the transducer of audio element.In these devices, the various parameters of element can be adjusted, so that in the resonance bending wave pattern of element, evenly distribute on frequency.Resonance bending wave pattern also can be distributed in the surface of element.This case has also disclosed the preferential position that transducer is installed on element.One typical preferential installation site is at an entad, but not at the center.Yet,, also other preferential positions can be arranged according to the shape of element.

Yet, always do not provide enough modal density easily, particularly at lower frequency.Therefore, if improved modal density or other raisings can be provided, it will have advantage, particularly to lower or intermediate frequency response.

The general introduction of invention

According to a first aspect of the invention, a kind of acoustics is provided, the actual shell continuously that comprises a support bending wave, shell is bent into to small part seals an air volume, so that bending wave is coupled to volume, so that the coupled resonance pattern to be provided, and a transducer that is coupled to shell, for will being coupled, and thereby be coupled to ambient sound again in the signal of telecommunication of transducer and coupled mode.

At device according to the present invention,, and have other pattern except the available resonance bending wave pattern of traditional distributed mode device institute.Calculating will provide after a while, and the increase pattern count of Air Coupling to shell is shown.Therefore, according to device of the present invention, can be increased in the existing pattern count of scheduled frequency range.

Preferably, the coupled resonance pattern evenly distributes on frequency in scheduled frequency range, and useful is that this frequency range is about and is higher than 1 to 2 or 3 octave of fundamental resonance frequency.In this scope, resonance bending wave pattern is for the most sparse, and in this scope distribution bending and the maximum benefit of isoplanar mode producing.

Shell can give complete closed, to surround this volume fully.Perhaps, can provide aperture or air vent hole at shell.Aperture or air vent hole can be designed to provides the particular resonance effect, and strengthens or be controlled at the boundary output of low sound equipment frequency range especially.

Though the unnecessary volume of sealing fully of shell, shell must reality be continuously, so that it can present effective sound equipment effect.In other words, shell must not have too many eyelet or fenestra.The height punctured element can't be suitable as the sound equipment radiant body, owing to will disturb devastatingly from the back from the radiation of element front, and from the anti-phase radiation of sending of the radiation of front.And shell should be enough continuous, and is remarkable to the coupling of sealing volume for shell.

The test of plate was once illustrated the very low coupling of punctured element and surrounding air.Therefore, shell can be not more than 20% of surface area in the delimited of its gross area, preferably be not more than 10%, is more preferred from and is not more than 5% hole.

Air in volume also may present chamber resonance.

According to acoustics of the present invention, support resonance bending wave pattern on the surface of three-dimensional case, and be coupled to a volume of being sealed by shell to small part.Contrast, traditional distributed mode loudspeaker has the resonance bending wave pattern that is distributed in a single panel.

In above-mentioned WO97/09842 number, suggestion is mounted to a distribution pattern panel front of one framework.In these prior-art devices, any resonance bending wave pattern practical limited is in the panel area, and unrestricted in framework.Therefore, these devices do not provide improved modal density, and thereby do not provide the improvement sound equipment that provides according to device of the present invention performance.

Another was before open, WO98/31188 number, a kind of flat that is installed in a pallet was described.Pallet gives highly perforation, and than solid area more fenestra zone is arranged, and therefore unactual continuous.Pallet is not operatively coupled to the air in pallet around will therefore not being operatively coupled to yet.

Shell can be fixed thickness.Perhaps the thickness of shell can give slowly or change continuously or faster.

Can provide fin or other extensions at shell.

Shell can be a single monolithic case.Perhaps shell can comprise combination of elements, and mechanical type is coupled to cause the sound equipment radiator structure of hope.In interelement combination, its boundary conditions may be stipulated valuably.

Shell can become a kind of polyhedron or its a part of form that many indivedual end faces are arranged.

Each end face can have a natural resonance frequency, and natural resonance frequency can be chosen as and have different value.This can increase the modal density of shell integral body.And different natural resonance frequencies can be chosen as causes resonance staggered on frequency in the pattern of different end faces.The method may be used in particular for increasing the modal density for low 10 to 20 modes of resonance.

Indivedual all end faces or separate board element need not to have even mechanical property, and it can be in rigidity, the isotropism of rigidity, and damping and amortization, or thickness changes to some extent.

Acoustics can be a loud speaker, and transducer is an exciter.

Acoustics can comprise the front/rear end of plate form, together with another plate at least, provides a path, for from the front to the mode of resonance of back, and the before and after plate that therefore is coupled.Before and after plate can reality be the plane.Before and after plate can borrow independent discrete exciter to be driven, or a single exciter can be coupled to before and after plate.

In all embodiment, the voice coil loudspeaker voice coil of an exciter can be coupled to one of all plates, and the magnet assembly of exciter is coupled to other plates.Because the magnet assembly is heavy, it is coupled to plate will cause the high-frequency decay.This can strengthen the bass response of acoustics.Many exciters can be provided.But exciter homophase, not homophase or driven each other in any suitable phase relation.

At a kind of traditional flat loud speaker, any isoplanar compressional wave all produces seldom or does not produce sound equipment output.This is because compression of the isoplanar of flat and expansion are not coupled to surrounding air.Contrast, at device according to the present invention, shell gives bending, thereby the isoplanar is compressed and expansion causes local or overall contraction and the expansion of shell, and its effect as is coupled to compressional wave and seals volume and be coupled to mechanism on every side.Therefore, the isoplanar compressional wave can help coupled mode valuably.In fact, at some embodiment, mode of resonance can be coupled bending wave, isoplanar pattern and the volume of sealing.Therefore can improve modal density.

According to a second aspect of the invention, a kind of acoustics is provided, comprise the actual shell continuously of sealing a volume, support many modes of resonance, coupling shell and the volume of sealing, mode of resonance is crossed over shell, and a transducer is coupled to shell, for the signal of telecommunication and mode of resonance being coupled, and thereby be coupled to ambient sound again at transducer.

At the device according to second aspect present invention, mode of resonance is crossed over the surface, from the front to the back side, from the side to the side, and from the top to the bottom.This allows in whole surface and the good model coupling of sealing volume.The whole surface of the unnecessary covering of pattern; Shell can for example have the not aperture or the zone of resonance.

A kind of method that drives acoustics is provided according to a further aspect in the invention, comprises: an actual shell continuously is provided, and shell is bent into to small part surrounds an air volume, and two transducers are provided, and two transducers are coupled to shell; Shell is supported bending wave, causes bending wave to be coupled to this volume, so that the coupled resonance pattern to be provided, with described two transducers of common signal of telecommunication driven in phase, causes the coupled mode of transducer drive shell and volume to become a kind of one pole configuration; And acoustic energy is radiated to surrounding air from coupled mode.

Brief description of drawings

Now with reference to the accompanying drawings, specific embodiment of the present invention is described, is intended to as an example, in the accompanying drawings:

Fig. 1 a demonstrates by a section according to the loud speaker of first embodiment of the invention, and this loud speaker has an elliposoidal shell;

Fig. 1 b demonstrates by another section according to the loud speaker of first embodiment of the invention, and this loud speaker has an elliposoidal shell;

Fig. 2 demonstrates by a section according to the loud speaker of second embodiment of the invention;

Fig. 3 demonstrates by a section according to the loud speaker of third embodiment of the invention, and this loud speaker has an aperture;

Fig. 4 demonstrates the section by the modification in an aperture;

Fig. 5 demonstrates a view according to the loud speaker of fourth embodiment of the invention, and this loud speaker is a kind of opening box form;

Fig. 6 demonstrates a view according to the loud speaker of fifth embodiment of the invention, and this loud speaker has a fully sheathed case;

Fig. 7 demonstrates the various exciting techniques that can cooperate loud speaker shown in Fig. 6 to use;

Fig. 8 demonstrates the exciter response at an airfree opening box;

Fig. 9 demonstrates the exciter response at opening box shown in Fig. 8, comprises the effect of Air Coupling;

Figure 10 a demonstrates the speed responsive at exciter, and this speed responsive is in the case among Fig. 8, the function of the frequency during no air;

Figure 10 b demonstrates the speed responsive at exciter, and this speed responsive is in the case among Fig. 9, the function of the frequency when comprising air effect;

Figure 11 demonstrates the pressure in the case of Fig. 9 b;

Figure 12 demonstrates the pattern that has in the loud speaker of fully sheathed case, two exciters is arranged in anti-phase driving;

Figure 13 demonstrates the pattern in the loud speaker of Figure 12, two exciters is arranged with in driven in phase;

Figure 14 demonstrates the speed responsive of the device in Figure 12 and 13;

Figure 15 demonstrates the speed responsive of one or six face closure casees, and wherein the flexural rigidity of front end face and rear end face do not match;

Figure 16 demonstrates one according to the present invention, becomes the view of the loud speaker of frustoconical bodily form formula;

Figure 17 demonstrates one according to the present invention, becomes the view of the loud speaker of tetrahedron form;

Figure 18 demonstrates one according to the present invention, becomes the view of the loud speaker of dodecahedron form;

Figure 19 demonstrates one according to the present invention, becomes the view of the loud speaker of cylinder form;

Figure 20 demonstrates one according to the present invention, becomes the view of the loud speaker of cone segments form;

Root mean square (rms) central authorities that Figure 21 demonstrates mode frequency are poor, and it is the function of the device front end face aspect ratio of Fig. 5;

Figure 22 demonstrates the VELOCITY DISTRIBUTION of three actuator position of the device of Fig. 5, and it has an aspect ratio is 2: 1 front end face;

Figure 23 demonstrates the figure of actuator position effect, and it is the function of exciter position on the device that Figure 22 used a model.

Describe in detail

Please refer to Fig. 1, a sealing spheroid shell 1 is sealed a volume 2, and has transducer 3,5 to be fixed on the inside of shell, is installed in opposed locations at the minor axis of spheroid.Shell 1 is supported from being coupled to the formed mode of resonance of resonance bending wave component of sealing volume.

Transducer is coupled to the signal of telecommunication coupled resonance pattern of shell and volume.In the present embodiment, transducer is an exciter, and it can be driven in use with the excitation coupled mode, produces sound equipment output.Transducer can be conventional version, and wherein a voice coil loudspeaker voice coil moves with respect to a ground connection magnet assembly when electric current passes through voice coil loudspeaker voice coil.Transducer can be inertia, and in this situation, the magnet assembly is free, and the inertia of the power effect of voice coil loudspeaker voice coil resistance magnet assembly.Perhaps, can use a ground connection transducer, in this situation, the magnet assembly is supported.In the present embodiment, in order to drive the commercial exciter of distribution pattern plate, be used in a kind of inertia configuration usually.

With known polarity driven transducer, so as to the polarization state that can wish in the sound generating of sending.For the one pole source, transducer can give driven in phase, and produces a dipole source, and transducer can be driven anti-phase.Perhaps, exciter can be driven in any suitable phase relation.

The present invention allows loud speaker not had the baffle use.In the conventional piston formula or distributed mode loudspeaker of using single vibrating diaphragm or plate, be anti-phase with from front institute radiation sound from the sound of back institute radiation.Therefore, avoid interference effect, must seal vibrating diaphragm by case and bag, or provide a baffle, arrive the front from the sound of back institute radiation so as to preventing around loud speaker.By driving according to loud speaker of the present invention as an one pole that has two transducer homophases to operate, can be so as to needing avoiding this baffle.

Coupled mode can be made of shell vibration coupling to the volume of sealing of two kinds of patterns.One of this two pattern is left the bending wave of the part plan of shell for making the shell bending.Another pattern is in the expansion on shell plane or contraction.

One complete flat will not provide this expansion-collapsed mode with coupling of resonance bending wave pattern.Though flat can have the expansion and the contraction of oscillation mode, it only makes plate move on himself plane, and does not influence the motion of surrounding air molecule.Therefore, in this isotype of flat, seldom or do not have a sound equipment effect.Contrast, if itself is enough to palintrope for plate, or even form a complete closed main body, just the isoplanar compressional wave modes causes the total volume expansion and the contraction of this main body, it can be coupled to air, and thereby has an audible effect.

The realistic model of shell vibration need not to be the pure bending wave mode, or the pure compression wave mode.On the contrary, the interfering with each other and coupling of each pattern possibility, and coupled mode is provided.Yet this isotype still may be possessed main bending wave characteristic.These ripples at shell are coupled to included volume then, to produce the mode of resonance of coupling.

Transducer is installed in minor axis, and unnecessary.May be conveniently as shown in Figure 2, it is installed from axle, or be in any appropriate location really.Preferably transducer is installed in a position that is chosen as for best or desired response.The geometry of laws of use such as spheroid, makes this than being easier to.Perhaps can use such as methods such as finite element analyses, to probe into suitable transducer position.Usually, may be suitably similar in appearance to the method for using distributed mode loudspeaker; Particularly the dissymmetric transducer position may prove suitable.With reference to Figure 21 to 23, the example of this situation is discussed after a while.

Using for some may be enough once single transducer; Other then can need some transducers to be distributed on shell.The layout of transducer may influence the directionality that shell is coupled to environment.

The volume of sealing is provided, allows to use all apertures to be controlled at the interior resonance of volume.Fig. 3 demonstrates an aperture 7 becomes a simple bore at an end of spheroid form.Perhaps can be as shown in Figure 4, provide one pipeline aperture 9 is arranged.

The aperture may cause the effect that produced at conventional piston formula type loud speaker or pipe similar in appearance to these apertures.All apertures can have asymmetric section.

Go out as shown above, volume is unnecessary whole by shell enclosure.On the contrary, all need, and be shell enough at itself replication, makes the mode of resonance of shell be coupled to the air of sealing in the volume, with the generation audible effect.Fig. 5 demonstrates an opening box, comprises a big front end face 11 that is surrounded by the framework 13 that constitutes with rectangular four sides 15 of front end face 11.Single transducer 3 is set, is connected to amplifier via sound equipment joint 9.Side 15 all gives sound equipment and is coupled to front end face 11.Resonance bending wave pattern at front end face 11 does not only remain on front end face, and is coupled to side (15).

Also can be embodied as into the form (Fig. 6) of a sealing involucrum for one the case, before and after end face 11,17 and four sides 13 are bonded to rear end face 17 with front end face 11, to form a sealing involucrum that includes a volume.Two transducers 3,5 are set, and each is at each end face 11,17.

One circuit 19 also is shown among Fig. 6, and it can switch between the anti-phase and noninverting driving of two transducers.One double-point double-throw switch 21 switches between the driven in parallel of transducer and antiparallel drive.

As shown in Fig. 7 a, transducer or before and after end face can be removed coupling.Perhaps the magnet assembly of two traditional moving-coil transducers can be coupled as shown in Fig. 7 b.Substitute as another, a single transducer can have its voice coil loudspeaker voice coil to be connected to front end face 11, and the magnet assembly is connected to rear end face 17, and the magnet assembly far overweights voice coil loudspeaker voice coil, and thereby assembly will preferentially be coupled low frequency to rear end face.Therefore, this configuration can be in order to increase the bass response of loud speaker.Before and after end face can be turned one's coat.

For a kind of five devices shown in Fig. 5, FEM (finite element) calculation of once carrying out the response of acoustics of being similar to.For simplicity, this configuration will be called opening box.Fig. 8 be illustrated in 178Hz (Fig. 8 a), at 348Hz (Fig. 8 b) and at 1000Hz (Fig. 8 c), during no air, the state of case responsing excitation.Fig. 9 is illustrated in same frequency, that is (Fig. 9 a) at 348Hz (Fig. 9 b), reaches at 1000Hz (Fig. 9 c), the state when having air at 178Hz.As finding out, response is not limited to arbitrary plane surface, but is coupling in whole five surfaces of case.And, have the complexity of the favourable increase shape of air.

The speed responsive of transducer, be the function of frequency shown in Figure 10: Figure 10 a illustrates airfree result, and Figure 10 b illustrates the result of air.The high speed that big value indication is reached in the excitation of this frequency.King-sized speed appears when resonance.As finding out, airfree response illustrates the big spike than peanut.This is peculiar by the mode of resonance than peanut.The air tank response in when envelope is being arranged, the spike of greater number is shown, each peak is then less.This more weak pattern by greater number is peculiar.As can finding out, be coupled to the pattern of the volume of sealing at plate, increase the number of mode of resonance, and thereby improve acoustics.Beyond thoughtly be, this effect is rather obvious, even at the case of opening.

Shown in Figure 11 when 348Hz, the air pressure in the case.Can know and find out asymmetric air pressure pattern.Causing the complex patterns shape of Air Coupling mode of resonance, is exactly that this air pressure distributes.

Once implement similar calculating to a kind of similar in appearance to the acoustics shown in Fig. 6, that is one have one before, six casees of sealing of a back and four sides.Partial results shown in Figure 12 and 13.All calculating include air.And coupled mode is coupling in all surface of case, before and after, and a left side and right flank, and top and bottom.

Figure 12 a demonstrates with homophase speed drive fully sheathed case, the pattern that is caused when 178Hz.Because before and after end face is towards rightabout, this is when with the transducer at the back plate plate being moved inward, and makes plate outwards move institute at the transducer of header board and reaches.This can borrow and for example use the transducer that is electrically connected of the switch difference shown in Fig. 6 to reach.Figure 12 b is illustrated in the vibration of 1000Hz.

Figure 13 a and 13b illustrate as one pole, and the before and after plate of case moves anti-phase, that is homophase is electrically connected to the same frequency pattern of transducer.As finding out, obtain Complex Response once more.

Air pressure when Figure 12 c and 13c are illustrated in 1000Hz with dipole and one pole driving respectively in the case is corresponding to the response of case shown in Figure 12 b and the 13b.Figure 12 c is clear to illustrate a kind of asymmetric response, even if driving and case are symmetry.Figure 13 c illustrates the very different pressures response that drives same cubicles by different way and just caused.

In Figure 14, provide the some transducer speed that obtained with fully sheathed case to frequency curve chart.Figure 14 a and 14b are illustrated in the response of the before and after end face (driving with one pole) of a symmetrical fully sheathed case coupling, and it can be expected.The dipole that Figure 14 c illustrates for same cubicles drives obtained significantly more inhomogeneous, and thereby relatively poor result.

Certainly, all above results are all only for calculating, but it illustrates really and use a shell at itself replication, with seal a volume possible improvement.

Figure 15 illustrates the case that the rigidity that is different from rear end face is arranged for its front end face, by two transducers, one in front (be shown in Figure 15 a), and one at rear end face, the velocity-response curve circle of (Figure 15 b) of driving.As finding out, the response of front end face advantageously is different from rear end face.Therefore, use is asymmetric can favourablely increase modal density in frequency.

It should be noted that, at all devices that goes out to have many end faces as shown in Figure 5, and such as having difference between the device that becomes a kind of full curve form among Fig. 1.Between end face in conjunction with 32 effects as hinge, and thereby resonance bending wave pattern not only do not march to an inferior facet from a facet.On the contrary, a kind of than complicated coupling of pattern appears.

Other multi-plane structures also may.Figure 16 to 20 demonstrates various forms, that is butt tetragonal pyramid body, tetrahedron, dodecahedron, cylinder and cone section.Each these form can be opening or sealing; For example cylinder can have or not have end face, and the cone section can have or not have rear end face.Indivedual all end faces may be separately formed, and give combination then, or all group of end face or even total can give whole formation.

Such as in WO97/09842 number discussion, be 0.707: 1 and 0.882 to 1 for a kind of good aspect ratio of isotropism rectangular slab.Also can adjust the characteristic of shell according to the present invention, so as to making the acoustics optimization, so that in the distribution maximum of the mode of resonance of frequency, and make the correct location of transducer onboard, so as to the good evenly coupling of transducer to pattern is provided.

This can use the technology of being discussed in variant distribution pattern patent application case to finish.Particularly, use a kind of method of order to find optimal aspect ratio and transducer position, so that on August 19th, 1999 to be provided, illustrated good as far as possible result in deliver with the name of New Transducer Ltd etc. WO99/41939 number.

In order to find out the appropriate characteristics for opening box, the first step of being implemented makes model with the variation of the aspect ratio of the opening box median plate among Fig. 5.Aspect ratio gives changing to 2.25 from 1, and borrows the respective frequencies of finite element analysis computation pattern.The root mean square central authorities difference of mode frequency is described aspect ratio (asking for an interview Figure 21).Central authorities' difference of the mode frequency of n pattern is that the frequency of (n+1) pattern adds (n-1) pattern person, subtracts the frequency of two times of n patterns.If all patterns give impartial spaced apart, this measurement will equal zero.Therefore, root mean square (rms) central authorities difference provides the figure of the advantage of various aspect ratios.Rms central authorities difference heals little better.

Can find out that from Figure 21 aspect ratio obtains good result between 1.6 and 2.2, particularly between 1.95 and 2.05, obtain good result.Getting aspect ratio 2 is a convenient value for further research.

Next stage is for to find the optimization drive point at end face.With regard to the function calculation speed responsive of some drive points position as frequency.Figure 22 produces three examples, at center 22a, and at the standard drive point of a flat distribution pattern plate 22b, and at optimal drive point 22c.Such as these persons' curve chart, its standard deviation is depicted as the function of the position in Figure 23.Optimum is with shown in the black, has minimum deflection person.It is not shown to examine the edge of knowing plate.These edges are bad drive point.

As check that this figure can find out, the optimal drive point appears at four positions, be positioned at along about 30% distance in long limit, reach 30% distance along minor face, and first the position around three other positions that central axis of symmetry found, to along major axis about 70% and along minor axis 30%, along axis 30% and 70% out of the ordinary, and the position of edge axis 70% out of the ordinary and 70%.These points are different from the optimal drive point for a simple rectangle, and its position is occurring in (3/7,4/9) place at the coordinate that is expressed as along the lateral distance ratio approximately near central authorities.

The position is for quite allowing variation, and can along long limit from 14% to 42%, and along minor face from 22% to 34% position, together with the symmetric points of this value, obtain good result.

Though implement above calculating, and do not take into account air influence, even for real device, it also provides the suitably good indication of transducer position when in length and breadth.Certainly, the characteristics such as anisotropy slightly such as Air Coupling or end face can make optimal aspect ratio and activation point mobile slightly.

The embodiment that has below illustrated is about loud speaker, and also being about to electric energy conversion is the device of sound.Method of the present invention is equally applicable to the incident acoustic energy is converted to electric flux by transducer microphone.

Claims (17)

1. an acoustics comprises

One actual shell (1) continuously, shell gives bending, so that small part is surrounded an air volume (2),

One transducer is coupled to shell (1), it is characterized in that, described shell (1) is supported equally distributed bending wave pattern, and described bending wave is coupled to this volume (2), so that the coupled resonance pattern to be provided, one signal of telecommunication is coupled with this coupled mode in transducer, thereby is coupled to ambient sound again.

2. acoustics as claimed in claim 1, wherein mode of resonance is crossed over shell.

3. the described acoustics of arbitrary as described above claim, wherein transducer (3) is an exciter, for the excitation mode of resonance, so that acoustics effect such as loud speaker.

4. acoustics as claimed in claim 1 or 2 wherein, has an aperture (7,9) on shell.

5. acoustics as claimed in claim 4, wherein this aperture (9) comprise a pipeline in shell stretches into volume (2).

6. acoustics as claimed in claim 1 or 2, wherein said shell comprise a plurality of end faces (11,13,15,17).

7. acoustics as claimed in claim 6, wherein each end face (11,13,15,17) has a natural resonance frequency, and natural resonance frequency has different value.

8. acoustics as claimed in claim 7, wherein different natural resonance frequencies are selected to cause the frequency of ten to 20 low-limit frequency modes of resonance for interlocking.

9. acoustics as claimed in claim 6, wherein shell comprises a front end face (11), and front end face has aspect ratio 1.6 to 2.2.

10. acoustics as claimed in claim 6, wherein shell comprises a rectangle front end face (11), and transducer (3) from one along the one side on long limit from 14% to 42%, and from one along one side of minor face from 22% to 34% position, the contact front end face.

11. acoustics as claimed in claim 6, wherein shell comprises opposed front end face (11) and rear end face (17).

12. acoustics as claimed in claim 11 wherein is provided with one first transducer at front end face, and at rear end face one second transducer (5) is set.

13. acoustics as claimed in claim 12, wherein first and second transducer (3,5) gives mechanical couplings.

14. acoustics as claimed in claim 11, wherein a single transducer (3) is coupled to before and after end face (11,17).

15. acoustics as claimed in claim 6, wherein shell (1) is a butt tetragonal pyramid body.

16. acoustics as claimed in claim 6, wherein shell (1) is a tetrahedron.

17. a method that drives acoustics comprises

One actual shell (1) continuously is provided, and shell is bent into to small part surrounds an air volume (2),

Two transducers (3,5) are provided, and two transducers are coupled to shell;

It is characterized in that shell is supported bending wave, causes bending wave to be coupled to this volume, so that the coupled resonance pattern to be provided, with described two transducers of common signal of telecommunication driven in phase (3,5), the coupled mode that causes transducer (3,5) to drive shell and volume becomes a kind of one pole configuration; And

Acoustic energy is radiated to surrounding air from coupled mode.

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