AMPLIFIER UNIT FOR A SOUND CONVERTER, AND SOUND-GENERATING UNIT

Abstract

The invention relates to an amplifier unit for a MEMS sound transducer, which is operable as a microphone and as a loudspeaker, comprising at least one audio amplifier for sound reproduction and/or sound recording. According to the invention, the amplifier unit is designed in such a way that the MEMS sound transducer provided therefor is simultaneously operable as a loudspeaker and as a microphone. Moreover, the invention relates to sound-generating unit comprising a MEMS sound transducer, which is operable as a microphone and as a loudspeaker, and an amplifier unit coupled to the sound transducer for sound reproduction and/or sound recording.

Claims

1. An amplifier unit (1) for a MEMS sound transducer (2), which is operable as a microphone and as a loudspeaker, comprising at least one audio amplifier (3a, 3b) for sound reproduction and/or sound recording, characterized in that the amplifier unit (1) is designed in such a way that the MEMS sound transducer (2) provided therefor is operable simultaneously as a loudspeaker and as a microphone.

2. The amplifier unit as claimed in the preceding claim, characterized in that the amplifier unit (1) comprises a processor (4), in particular a digital signal processor, with the aid of which the MEMS sound transducer (2) provided therefor can be utilized as a microphone at the same time as the sound generation.

3. The amplifier unit as claimed in one or more of the preceding claims, characterized in that the processor (4) is designed, for sound cancellation, in such a way that it can filter out and/or suppress ambient noise on the basis of the emitted audio signal and the acoustic signal detected at the same time with the aid of the same MEMS sound transducer (2).

4. The amplifier unit as claimed in one or more of the preceding claims, characterized in that the processor (4) is designed in such a way that it separates an acoustic signal, which is detected by the MEMS sound transducer (2) operating as a microphone, into a first acoustic signal component representing the emitted useful sounds and into a second acoustic signal component representing the ambient noise.

5. The amplifier unit as claimed in one or more of the preceding claims, characterized in that the processor (4) is designed in such a way that it generates an anti-noise signal on the basis of the second acoustic signal component and combines the anti-noise signal with an input signal including useful sound to form the audio signal.

6. The amplifier unit as claimed in one or more of the preceding claims, characterized in that the processor (4) is designed in such a way that it can switch the MEMS sound transducer (2) between the operation as a loudspeaker and the operation as a microphone.

7. The amplifier unit as claimed in one or more of the preceding claims, characterized in that the amplifier unit (1) comprises a hybrid audio amplifier (3c), with the aid of which the audio signal can be output to the MEMS sound transducer (2) provided therefor, for sound reproduction, and the acoustic signal of the MEMS sound transducer (2) can be received, for sound recording.

8. The amplifier unit as claimed in one or more of the preceding claims, characterized in that the amplifier unit (1) comprises a loudspeaker amplifier (3a) for the sound reproduction of the audio signal and a microphone amplifier (3b) for the sound recording of the acoustic signal.

9. The amplifier unit as claimed in one or more of the preceding claims, characterized in that the audio amplifier (3a, 3b) is designed in such a way that, with the aid thereof, the, in particular piezoelectric, MEMS sound transducer (2) is operable.

10. The amplifier unit as claimed in one or more of the preceding claims, characterized in that the amplifier unit (1) comprises at least one signal processor (5a, 5b), which is connected to the at least one audio amplifier (3a, 3b) and with the aid of which the audio signal can be preconditioned for sound reproduction and/or the acoustic signal can be conditioned for sound recording.

11. The amplifier unit as claimed in one or more of the preceding claims, characterized in that the processor (4) comprises a data link (11) to the at least one audio amplifier (3a, 3b) and/or to the at least one signal processor (5a, 5b), with the aid of which the emitted audio signals and detected acoustic signals and the audio data to be processed in the signal processor (5a, 5b) can be transmitted to the processor (4).

12. The amplifier unit as claimed in one or more of the preceding claims, characterized in that the amplifier unit (1) comprises at least one, in particular wired and/or bidirectional, interface (10), via which audio signals can be transmitted from the amplifier unit (1) to the MEMS sound transducer (2) and acoustic signals can be transmitted from the MEMS sound transducer (2) to the amplifier unit (1), preferably at the same time.

13. The amplifier unit as claimed in one or more of the preceding claims, characterized in that the amplifier unit (1) is arranged on a single chip.

14. A sound-generating unit comprising a MEMS sound transducer (2), which is operable as a microphone and as a loudspeaker, and an amplifier unit (1) coupled to the MEMS sound transducer (2) for sound reproduction and/or sound recording, characterized in that the amplifier unit (1) is designed as claimed in one or more of the preceding claims.

15. The sound-generating unit as claimed in the preceding claim, characterized in that the MEMS sound transducer (2) is designed as a simultaneous sound transducer, which, operating as a loudspeaker, can output an audio signal and, at the same time, operating as a microphone, can record an acoustic signal.

16. The sound-generating unit as claimed in one or more of the preceding claims, characterized in that the MEMS sound transducer (2) is a piezoelectric MEMS sound transducer.

17. The sound-generating unit as claimed in one or more of the preceding claims, characterized in that the amplifier unit (1) and the MEMS sound transducer (2) are arranged on a single chip.

18. The sound-generating unit as claimed in one or more of the preceding claims, characterized in that the MEMS sound transducer (2) comprises at least one sound transducer unit (21, 22) coupled to a diaphragm (13) of the MEMS sound transducer (2), which can deflect the diaphragm (13) of the MEMS sound transducer (2) for sound generation and can detect a deflection of the diaphragm (13) for sound detection.

19. The sound-generating unit as claimed in one or more of the preceding claims, characterized in that the at least one sound transducer unit (21, 22) comprises at least two sound transducer layers (29, 30), wherein the diaphragm (13) is deflectable with the aid of one sound transducer layer (29, 30) and the deflection of the diaphragm (13) is detectable with the aid of the other sound transducer layer.

20. The sound-generating unit as claimed in one or more of the preceding claims, characterized in that the MEMS sound transducer (2) comprises at least one first sound transducer unit (21) coupled to the diaphragm (13) and at least one second sound transducer unit (22) coupled to the diaphragm (13), wherein one of the two sound transducer units (21, 22) can deflect the diaphragm (13) and the other sound transducer unit (21, 22) can detect the deflection of the diaphragm (13).

21. The sound-generating unit as claimed in one or more of the preceding claims, characterized in that the at least one sound transducer unit (21, 22) and/or at least one of the two sound transducer layers (29, 30) are/is connected to a processor (4) of the amplifier unit (1), so that the processor (4) can deflect the diaphragm (13) for sound generation and can detect the deflection for sound detection with the aid of the at least one sound transducer unit (21, 22) and/or at least one of the two sound transducer layers (29, 30).

22. The sound-generating unit as claimed in one or more of the preceding claims, characterized in that the at least two sound transducer units (21, 22) of the MEMS sound transducer (2) are connected to one another with the aid of an, in particular, elastic connecting element (24).

23. The sound-generating unit as claimed in one or more of the preceding claims, characterized in that the MEMS sound transducer (2) comprises a limiting element (23), with the aid of which the diaphragm (13) is limited in the deflection in at least one direction of a reciprocation axis (20) of the sound transducer (2).

24. The sound-generating unit as claimed in one or more of the preceding claims, characterized in that the diaphragm (13), in particular separated by the limiting element (23), comprises a first diaphragm area (25) and a second diaphragm area (26), wherein one of the sound transducer units (21, 22) can deflect the diaphragm (13) in the first diaphragm area (25) for sound generation and the other sound transducer unit (21, 22) can detect the deflection of the diaphragm (13) in the second diaphragm area (26) for sound recording.

Description

[0043] Additional advantages of the invention are described in the following exemplary embodiments. The drawings show in:

[0044] FIG. 1 a block diagram of an amplifier unit comprising two audio amplifiers, a processor, and two signal processors,

[0045] FIG. 2 a block diagram of an alternative exemplary embodiment of an amplifier unit comprising two audio amplifiers, a processor, and two signal processors,

[0046] FIG. 3 a block diagram of an alternative exemplary embodiment of an amplifier unit comprising a hybrid audio amplifier, a processor, and two signal processors,

[0047] FIG. 4 a schematic sectional view of a sound transducer comprising a support element and a diaphragm,

[0048] FIG. 5 a schematic sectional view of a further exemplary embodiment of a sound transducer,

[0049] FIG. 6 a schematic sectional view of a further exemplary embodiment of a sound transducer, and

[0050] FIG. 7 a schematic sectional view of a further exemplary embodiment of a sound transducer,

[0051] FIG. 1 shows a block diagram of an amplifier unit 1 for operating a sound transducer 2, comprising two audio amplifiers 3a, 3b, a processor 4, and two signal processors 5a, 5b. In this exemplary embodiment, the audio amplifier 3a is designed as a loudspeaker amplifier, which amplifies an audio signal for the sound transducer 2, so that the sound transducer 2 can be operated as a loudspeaker. In this exemplary embodiment, the audio amplifier 3b is designed as a microphone amplifier, which amplifies an acoustic signal coming from the sound transducer 2, so that the sound transducer 2 can be operated as a microphone.

[0052] Moreover, the audio amplifier 3a and the signal processor 5a in this exemplary embodiment are combined to form a loudspeaker unit 6 and the audio amplifier 3b and the signal processor 5b are combined to form a microphone unit 7. For example, the loudspeaker unit 6 and/or the microphone unit 7 can be produced as one component, in particular on a single chip, and are combined to form the amplifier unit 1.

[0053] The amplifier unit 1 comprises an audio input 8 for the feed-in of an audio signal, for example, the music and/or the speech, which leads into the loudspeaker unit 9 and/or into the signal processor 5b. Alternatively, the audio input 8 can also conduct the audio signal directly into the loudspeaker amplifier 3b. The audio input 8 can feed, for example, a music signal from an MP3 player, a CD player, and/or a radio signal, for example, from a mobile phone, into the amplifier unit 1.

[0054] In order to feed-out the audio signal, the amplifier unit 1 comprises an audio outlet 9, which leads out of the microphone unit 7 and/or away from the signal processor 5a. The audio output 9 can also conduct the music or speech signal to a memory unit and/or to a mobile phone, where it is stored or sent to a conversation partner.

[0055] Furthermore, the audio input 8 and the audio output 9 can comprise an interface (not shown here), so that the audio signal can be conducted into and/or out of the amplifier unit 1, for example, in a wired manner.

[0056] The amplifier unit 1 comprises an interface 10 so that the sound transducer 2 can be connected to the amplifier unit 1. The interface 10 and/or the interfaces of the audio input 8 and/or of the audio output 9 can be wired and/or bidirectional and/or designed, for example, as an audio jack, an RCA connector, an XLR connector, a speakON connector, and/or a USB connection, so that, for example, the sound transducer 2 can be detachably connected to the amplifier unit 1. Additionally or alternatively, the interfaces can also be optically designed.

[0057] Additionally or alternatively, the sound transducer 2 can also be fixedly coupled to the interface 10, for example, with the aid of a soldered connection.

[0058] In this exemplary embodiment, the processor 4 is arranged between the audio amplifier 3a and the audio amplifier 3b and is connected to each of the two audio amplifiers. 3a, 3b with the aid of data links 11 (only one data link is provided with a reference numeral, for the sake of simplicity). Moreover, a data link 11 extends from the processor 4 to the interface 10.

[0059] The data link 11 can also be designed to be wired and/or bidirectional. The data link 11 can be designed for transmitting an electrical and/or optical signal. Furthermore, the data link 11 can also be designed as a strip conductor on a circuit board.

[0060] The amplifier unit 1 can also be arranged, for example, in headphones, in a headset, in in-ear headphones, in a helmet comprising a loudspeaker or loudspeakers, or in a mobile phone, wherein music, tones, and/or speech can be played back and/or recorded by the sound transducer 2 with the aid of the amplifier unit 1. When music is to be recorded, the sound transducer 2 can be utilized as a microphone. When music is to be played back, the sound transducer 2 can be utilized as a loudspeaker.

[0061] With the aid of the amplifier unit 1 according to the invention, an active noise reduction (ANR) method can &so be carried out. For this purpose, the amplifier unit 1 is designed in such a way that it can operate the sound transducer 2 simultaneously as a microphone for sound recording and as a loudspeaker for sound reproduction.

[0062] In this case, “simultaneously” can also mean that the listener of the music, the tones, or the speech merely gets the impression that the cancellation of the ambient noise with the aid of the anti-noise takes place at the same time. For example, due to a finite temporal resolution of human hearing, it can suffice when the cancellation of the ambient noise with the aid of the anti-noise takes place within the shortest temporal resolution of human hearing.

[0063] With the aid of the processor 4, which can also be designed as a digital signal processor, the sound transducer 2 can be utilized as a microphone at the same time during the sound generation.

[0064] For example, the processor 4 can comprise an arithmetic logic unit in which a computer program is run, which processes the sound recorded by the sound transducer 2. The processor 4 can, for example, filter the ambient noise out of the recorded sound. The processor 4 can also form the anti-sound on the basis of the ambient noise, which is played back by the sound transducer 2 together with the music and cancels out the ambient noise. The playback of the music and of the anti-noise can take place at the same time as the recording of the ambient noise, so that the ambient noise is cancelled out essentially immediately by the corresponding anti-noise.

[0065] The sound transducer 2, as a microphone, therefore records, for example, music and ambient noise. The amplifier unit 1 isolates the ambient noise and, on the basis thereof, generates a corresponding anti-noise. The anti-noise is reproduced, together with the music to be played back, by the sound transducer 2, which is now utilized as a loudspeaker. The anti-noise can be played back with the music by the sound transducer 2 at the same time as the recording of the ambient noise. The anti-noise component of the sound generated in this way destructively interferes with the ambient noise and, as a result, cancels out the ambient noise. All that remains is the music, which is perceived by a listener.

[0066] Due to the recording of the sound, which includes, in particular, the ambient noise, and the simultaneous generation of the sound by the single sound transducer 2, the active noise reduction method can be carried out with a high level of quality. The cancellation of the ambient noise with the aid of the corresponding anti-noise takes place with the aid of the one sound transducer 2 at the spot at which the ambient noise is also recorded. As a result, no propagation times between the spot of the recording of the ambient noise and the spot of the reproduction of the anti-noise need to be taken into account in the computation of the anti-noise, and so the anti-noise can be calculated faster.

[0067] The amplifier unit 1 can also be manufactured on a chip in one manufacturing step, however. For example, the audio amplifiers 3a, 3b, the processor 4, the signal processors 5a, 5b, and/or the data links 11 can be arranged on the chip. Additionally or alternatively, the interface 10 and/or the interfaces of the audio input 8 and/or of the audio output 9 can also be arranged on the chip.

[0068] FIG. 2 shows an alternative exemplary embodiment of the amplifier unit 1 in a block diagram. The features and functions identical to those described with respect to FIG. 1 are not described again, from this point forward, for the sake of simplicity. In this exemplary embodiment, the processor 4 is arranged between the loudspeaker unit 6 and the microphone unit 7. The processor 4 comprises a data link 11 to the loudspeaker unit 6 as well as to the microphone unit 7. The processor 4 is coupled between the signal processor 5a and the audio amplifier 3a with the aid of the data link 11. In addition, the processor 4 is coupled between the signal processor 5b and the audio amplifier 3b with the aid of the data link 11.

[0069] In this exemplary embodiment, the processor 4 can further process the sound, which includes, in particular, the ambient noise and the music, and which has been processed by the audio amplifier 3b. In particular, the processor 4 can generate the anti-noise on the basis of the ambient noise. The processor 4 can subsequently conduct the anti-noise into the loudspeaker unit 6, in which the anti-noise is conducted with the aid of the audio amplifier 3a to the sound transducer 2 for sound reproduction.

[0070] FIG. 3 shows a further alternative exemplary embodiment of the amplifier unit 1 comprising a sound transducer 2, a hybrid audio amplifier 3c, a processor 4, and two signal processors 5a, 5b.

[0071] In this exemplary embodiment, the amplifier unit 1 comprises a single hybrid audio amplifier 3c, which can amplify the audio signal for sound reproduction, in order to feed the audio signal to the sound transducer 2, and which can process, in particular simultaneously, the audio signal from the sound transducer 2 for sound recording, in order to store the acoustic signal, for example. The hybrid audio amplifier 3c can also, for example, filter the ambient noise out of the recorded acoustic signal and generate the anti-noise on the basis thereof. The hybrid audio amplifier 3c can also amplify the anti-noise again and conduct it, together with the music, to the sound transducer 2 for sound reproduction.

[0072] Additionally or alternatively, the processor 4 can also filter the ambient noise out of the recorded acoustic signal and generate the anti-noise.

[0073] FIG. 4 shows a schematic sectional view of a sound transducer 2 comprising a support element 12 and a diaphragm 13. The sound transducer 2 comprises a support element 12, on which a diaphragm 13 is arranged. With the aid of the diaphragm 13, air situated above the diaphragm 13 can be caused to vibrate, so that sound waves are generated. As a result, the sound transducer 2 is operated as a loudspeaker. Additionally, air above the diaphragm 13, which is vibrating due to the sound waves, can cause the diaphragm 13 to vibrate. As a result, the sound transducer 2 is operated as a microphone. The diaphragm 13 can be deflected along a reciprocation axis 20.

[0074] According to the present exemplary embodiment, the sound transducer 2 comprises a first sound transducer unit 21 and a second sound transducer unit 22.

[0075] Furthermore, the first sound transducer unit 21 can comprise a first sound transducer element 14, which is connected to the diaphragm 13 in the present case with the aid of a first coupling element 16. The second sound transducer unit 22 can comprise a second sound transducer element 15, which is connected to the diaphragm 13 in the present case with the aid of a second coupling element 17. The two coupling elements 16, 17 can be fixedly connected to the diaphragm 13.

[0076] According to the present exemplary embodiment, a coupling plate 27, 28 is arranged between the coupling elements 16, 17, respectively, and the diaphragm 13. Due to the particular coupling plate 27, 28, a planar transmission of the deflection between the diaphragm 13 and the sound transducer unit 21, 22, respectively, can be made possible.

[0077] The first sound transducer element 14 and/or the second sound transducer element 15 can comprise, for example, a piezoelectric element, so that an electrical signal can be converted into a deflection of the sound transducer element 14, 15 and/or a deflection of the sound transducer element 14, 15 can be converted into an electrical signal. Since the first sound transducer element 14 and/or the second sound transducer element 15 are/is connected to the diaphragm 13 with the aid of the corresponding coupling element 16, 17, the deflections of the sound transducer elements 14, 15 can be transmitted onto the diaphragm 13 and/or the vibrations of the diaphragm 13 can be transmitted onto the sound transducer elements 14, 15.

[0078] Advantageously, for example, the first sound transducer unit 21 can be operated as a loudspeaker. Sound waves can therefore be generated with the aid of the first sound transducer unit 21. Additionally, the second sound transducer unit 22 can be operated as a microphone. The sound waves can therefore be recorded with the aid of the second sound transducer unit 22. The first sound transducer unit 21 can be operated simultaneously with or at the same time as the second sound transducer unit 22, so that sound waves can be generated and detected simultaneously or at the same time with the aid of the sound transducer 2. Since both sound transducer units 21, 22 are coupled to a diaphragm 13, the sound waves can be generated and detected with the aid of the sound transducer 2.

[0079] For example, the first sound transducer unit 21 is operated as a loudspeaker, so that sound waves are generated on the basis of an audio signal, which, in turn, can include music, tones, and speech, as well as the anti-noise.

[0080] The second sound transducer unit 22 can be operated, for example, as a microphone, so that an acoustic signal is detected on the basis of the sound waves. The detected acoustic signal can comprise two acoustic signal components. A first acoustic signal component can include, for example, the ambient noise. Additionally, a second acoustic signal component can include the speech, the tones, and the music, and/or the anti-noise, which are/is generated at the same time by the first sound transducer unit 21. The detected acoustic signal is therefore composed of the first acoustic signal component and the second acoustic signal component. Since the second acoustic signal component is known, however, since it corresponds to the audio signal generated at the first sound transducer unit 22, this second acoustic signal component can be filtered out of the acoustic signal. For example, the second acoustic signal component can be subtracted from the acoustic signal. A difference signal can be ascertained. As a result, the first acoustic signal component, which includes the ambient noise, can be ascertained.

[0081] According to the present exemplary embodiment of FIG. 4, the first sound transducer unit 21 is arranged in a first sound transducer area 18. Additionally or alternatively, the second sound transducer unit 22 according to the present exemplary embodiment is arranged in a second sound transducer area 19. The two sound transducer areas 18, 19 can have a distance A from one another. Additionally or alternatively, the two sound transducer units 21, 22 can also have the distance A from one another. Due to the distance A, the coupling elements 16, 17 are also spaced apart from one another, which transmit the deflection between the diaphragm 13 and the corresponding sound transducer elements 14, 15. As a result, the two sound transducer units 21, 22 for generating and/or detecting the sound waves have very little effect on one another.

[0082] For example, the first sound transducer unit 21 is operated as a loudspeaker, so that sound waves are generated therewith. The coupling element 16 transmits the deflections of the first sound transducer element 14 in the first sound transducer area 18 onto the diaphragm, which forms corresponding vibrations, The second sound transducer unit 22 can be operated as a microphone at the same time as or simultaneously with the first sound transducer unit 22. With the aid of sound waves, the diaphragm 13 in the second sound transducer area 19 is caused to vibrate; the vibrations are transmitted by the coupling element 17 onto the second sound transducer element 15. Therefore, sound waves can be generated and detected at the same time or simultaneously with the aid of a single sound transducer 2.

[0083] Alternatively, both sound transducer units 21, 22 can also be operated as a loudspeaker and/or as a microphone. For example, the two sound transducer units 21, 22 can be operated as loudspeakers in a loudspeaker interval and as microphones in a temporally subsequent microphone interval.

[0084] FIG. 5 shows a schematic sectional view of a further exemplary embodiment of a sound transducer 2. For the sake of simplicity, the features that are the same as in the preceding figures will not be explained again.

[0085] For example, the diaphragm 13 in the first diaphragm area 25 can be set into vibration with the aid of the first sound transducer unit 21, so that sound waves are generated. The diaphragm 13 is therefore utilized in the first diaphragm area 25 for the loudspeaker function of the sound transducer 2. In the second diaphragm area 26, sound waves can set the diaphragm 13 into vibration; the vibrations can be detected by the second sound transducer unit 22. The diaphragm 13 is therefore utilized in the second diaphragm area 26 for the microphone function of the sound transducer 2.

[0086] Moreover, the diaphragm 13 can comprise a first diaphragm area 25 and a second diaphragm area 26. According to the present exemplary embodiment, the two diaphragm areas 25, 26 are arranged adjacent to one another on the diaphragm 13. In this exemplary embodiment of FIG. 5, a limiting element 23 is arranged between the two diaphragm areas 25, 26.

[0087] With the aid of the limiting element 23, a deflection of the diaphragm 13 in the area of the limiting element 23 along the reciprocation axis 20 can be limited. For example, the diaphragm 13 can rest, in particular loosely, on the limiting element 23, so that a deflection along the reciprocation axis 20 in the direction of the limiting element 23 is prevented. Additionally or alternatively, the diaphragm 13 can also be connected to the limiting element 23, so that a deflection along the reciprocation axis 20 is limited in both directions. The diaphragm 13 can be adhesively bonded, for example, on the limiting element 23. The limiting element 23 can be designed, for example, as one piece with the support element 12.

[0088] The first sound transducer area 18 can be arranged in the first diaphragm area 25 and the second sound transducer area 19 can be arranged in the second diaphragm area 26.

[0089] FIG. 6 shows a schematic sectional view of a further exemplary embodiment of a sound transducer 2.

[0090] According to the present exemplary embodiment, the two sound transducer units 21, 22 are connected to one another with the aid of a connecting element 23. The connecting element 23 couples the two sound transducer units 21, 22, so that the deflections of the sound transducer units 21, 22 are transmitted onto the particular other sound transducer unit 21, 22. According to the present exemplary embodiment, the connecting element 23 is arranged between the two coupling elements 16, 17 of the two sound transducer units 21, 22, respectively.

[0091] Furthermore, the connecting element 24 can be elastically designed, so that a change of the distance A due to the deflection of the sound transducer elements 21, 22 can be compensated for. The connecting element 24 can comprise, for example, a spring element.

[0092] Moreover, the first sound transducer unit 21 and/or the second sound transducer unit 22 can be connected to the at least one audio amplifier 3. If, for example, the first sound transducer unit 21 is operated as a loudspeaker in order to generate the sound waves, the first sound transducer unit 21 can be connected to the audio amplifier 3 that is operated as a loudspeaker amplifier. When the first sound transducer unit 21 is operated as a loudspeaker, it can be connected, for example, to the audio amplifier 3a from FIGS. 1 and 2. If, for example, the second sound transducer unit 22 is operated as a microphone, for example, in order to detect the sound waves, the second sound transducer unit 22 can also be connected to an audio amplifier 3. If the second sound transducer unit 22 is operated, for example, as a microphone, it can be connected, for example, to the audio amplifier 3b from FIGS. 1 and 2.

[0093] FIG. 7 shows a schematic sectional view of a further exemplary embodiment of a sound transducer 2. According to the present exemplary embodiment, the sound transducer element 14 can comprise a first sound transducer layer 29 and a second sound transducer layer 30. Both sound transducer layers 29, 30 can form the sound transducer element 14 in this case. The two sound transducer layers 29, 30 can be arranged one above the other in the direction of the reciprocation axis 20. The two sound transducer layers 29, 30 can each be designed as a piezoelectric element. The first sound transducer element 14 of the present exemplary embodiment can be formed by two piezoelectric elements arranged one above the other.

[0094] It is advantageous when one of the two sound transducer layers 29, 30 is operated as a loudspeaker in order to generate the sound waves and the other sound transducer layer 29, 30 is operated as a microphone in order to detect the sound waves. Therefore, the sound waves can be generated with the aid of one sound transducer layer 29, 30 and the sound waves can be detected with the aid of the other sound transducer layer 29, 30.

[0095] The sound waves can therefore be generated by, for example, the first sound transducer layer 29 and, at the same time or simultaneously therewith, the sound waves can be detected with the aid of the second sound transducer unit 30.

[0096] Furthermore, the two sound transducer layers 29, 30 can be connected to the particular audio amplifiers 3a, 3b. The sound transducer layer 29, 30 that is operated as a loudspeaker can be connected to the audio amplifier 3a, 3b that is operated as a loudspeaker amplifier, and the sound transducer layer 29, 30 that is operated as a microphone can be connected to the audio amplifier 3a, 3b that is operated as a microphone amplifier.

[0097] Alternatively, the sound transducer 2 can also comprise two sound transducer units 21, 22, similarly to the preceding figures, including at least two sound transducer layers 29, 30.

[0098] The present invention is not limited to the represented and described exemplary embodiments. Modifications within the scope of the claims are also possible, as is any combination of the features, even if they are represented and described in different exemplary embodiments.

LIST OF REFERENCE NUMERALS

[0099] 1 amplifier unit [0100] 2 MEMS sound transducer [0101] 3 audio amplifier [0102] 4 processor [0103] 5 signal processor [0104] 6 loudspeaker unit [0105] 7 microphone unit [0106] 8 audio input [0107] 9 audio output [0108] 10 interface [0109] 11 data link [0110] 12 support element [0111] 13 diaphragm [0112] 14 first sound transducer unit [0113] 15 second sound transducer unit [0114] 16 first coupling element [0115] 17 second coupling element [0116] 18 first sound transducer area [0117] 19 second sound transducer area [0118] 20 reciprocation axis [0119] 21 first sound transducer unit [0120] 22 second sound transducer unit [0121] 23 limiting element [0122] 24 connecting element [0123] 25 first diaphragm area [0124] 26 second diaphragm area [0125] 27 first coupling plate [0126] 28 second coupling plate [0127] 29 first sound transducer layer [0128] 30 second sound transducer layer [0129] A distance