Hybrid horn microphone

• US 10,375,474 B2
• Filed: 06/12/2017
• Issued: 08/06/2019
• Est. Priority Date: 06/12/2017
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Skramstad, Rune, Sun, Haohai
• Primary Examiner(s): Mei, Xu
• Assistant Examiner(s): Hamid, Ammar T
• Application Number:
  US15/620,169
• Publication Number:
  US 20180359562A1
• Time in Patent Office: 785 Days
• Field of Search: 381 92, 381337
• CPC Class Codes: H04R 1/30 Combinations of transducers with horns, e.g. with mechanical matching means , i.e. front-loaded hornshorns in general G10K; transducer enclosures or mountings using a back-loaded horn H04R1/2861; application of horns as guiding means to obtain a predetermined directivity characteristic H04R1/345
• CPC Class Codes: H04R 1/406 microphones
• CPC Class Codes: H04R 2201/401 2D or 3D arrays of transducers
• CPC Class Codes: H04R 2430/03 Synergistic effects of band splitting and sub-band processing
• CPC Class Codes: H04R 3/005 for combining the signals of two or more microphones specially adapted for hearing aids H04R25/407
• CPC Class Codes: H04R 3/04 for correcting frequency response

Abstract

The disclosed technology relates to a microphone array. The array comprises a plurality of microphones with each microphone having a horn portion. Each microphone of the array further comprises an instrument disposed at a distal end of the horn portion. Each instrument of the array is configured to convert sound waves into an electrical signal. The microphone array further comprises a beamforming signal processing circuit electrically coupled to each instrument and configured to create a plurality of beam signals based on respective electrical signals.

Claims

1. A system for converting sound waves, the system comprising:

an array of microphones, the array comprising a plurality of microphones, each microphone of the plurality of microphones comprising;

a horn portion comprising at least three planar surfaces, the surfaces arranged in a converging orientation to form a shape having a first opening at a proximal end and a second opening at a distal end, the second opening at the distal end being smaller in area than the first opening at the proximal end; and

an instrument disposed at the distal end of the horn portion, the instrument configured to convert sound waves into an electrical signal;

the microphones of the array are radially disposed around a central point to define a polyhedron shape and oriented to direct received sound waves to that central point; and

a beamforming signal processing circuit electrically coupled to each instrument of the plurality of microphones and configured to create a plurality of beam signals based on the respective electrical signals of each instrument.

2. The system of claim 1, wherein the beamforming signal processing circuit comprises a crossover filter, a processor, a delaying circuit, and a mixer.

3. The system of claim 2, wherein the crossover filter is configured to convert the electrical signal from each instrument of the plurality of microphones to respective first signals and second signals.

4. The system of claim 3, wherein the processor is configured to:

downsample each of the first signals from the crossover filter to create respective downsampled first signals;

process each of the downsampled first signals to create respective processed first signals, the processed first signals indicative of a location of the source of the sound waves detected by the respective instrument; and

upsampled each of the processed first signals to create respective upsampled first signals.

5. The system of claim 4, wherein the delaying circuit is configured to delay each of the second signals from the crossover filter to create respective delayed second signals.

6. The system of claim 5, wherein the mixer is configured to combine each of the upsampled first signals from the processor with corresponding delayed second signals from the delaying circuit to create the plurality of beam signals.

7. The system of claim 1, further comprising an audio processing circuit, the audio processing circuit configured to perform at least one of an echo control filer, a reverberation filter, or a noise reduction filter, to the plurality of beam signals from the beamforming signal processing circuit.

8. The system of claim 1, wherein the shape of the horn portion formed by the plurality of surfaces comprises a square pyramid having four interior faces.

9. The system of claim 1, wherein the shape of the horn portion formed by the plurality of surfaces comprises a pentagonal pyramid having five interior faces.

10. The system of claim 1, wherein the shape of the horn portion formed by the plurality of surfaces comprises a hexagonal pyramid having six interior faces.

11. The system of claim 1, wherein each beam signal of the plurality of beam signals is indicative of a location of a source of the sound waves detected by each respective instrument.

12. A microphone array comprising:

a plurality of microphones arranged to form an array, the microphones of the array being radially disposed around a central point to define a polyhedron shape and oriented to direct received sound waves to that central point, each microphone of the plurality of microphones comprising;

a horn portion comprising a at least three planar surfaces, the planar surfaces arranged in a converging orientation to form a shape having a first opening on a proximal end and a second opening on a distal end, the second opening on the distal end being smaller in area than the first opening on the proximal end; and

an instrument disposed on the distal end of the horn portion, the instrument configured to detect sound waves and convert sound waves into an electrical signal;

a beamforming signal processing circuit electrically coupled to each instrument of plurality of microphones, the beamforming signal processing circuit configured to;

receive a plurality of electrical signals, the plurality of electrical signals comprising the electrical signal from each microphone of the plurality of microphones; and

create a plurality of beam signals based on the plurality of electric signals each beam signal of the plurality of beam signals corresponding to the electrical signal from each microphone of the plurality of microphones.

13. The microphone array of claim 12, wherein the beamforming signal processing circuit comprises a crossover filter, a processor, a dealying circuit, and a mixer.

14. The microphone array of claim 12, further comprising an audio processing circuit, the audio processing circuit configured to perform at least one of an echo control filter, a reverberation filter, or a noise reduction filter, to the plurality of beam signals from the beamforming signal processing circuit.

15. The microphone array of claim 12, further comprising an automatic mixer, the automatic mixer configured to receive the plurality of beam signals and identify a beam signal from the plurality of beam signals based on a characteristic of the beam signal.

16. The microphone array of claim 12, wherein the shape of the horn portion of each microphone of the plurality of microphones comprises a pentagonal pyramid having five interior faces.

17. The microphone array of claim 12, wherein the array comprises a polyhedron shape.

18. The microphone array of claim 17, wherein the polyhedron shape comprises a half dodecahedron.

19. The microphone array of claim 12, wherein each beam signal is indicative of a location of a source of the sound waves detected by each microphone of the plurality of microphones.

20. A method for creating a plurality of beam signals, the method comprising:

receiving a sound wave at an array of microphones, the array of microphones comprising a plurality of microphones each having a horn portion comprising at least three planar surfaces radially disposed around a central point to define a polyhedron shape and oriented to direct received sound waves to that central point, each microphone comprising a horn portion and an instrument, the instrument configured to generate an electrical signal based on the sound wave;

generating a plurality of electrical signals based on the received sound wave, the plurality of electrical signals comprising the electrical signal generated by each instrument of the plurality of microphones;

converting each electrical signal of the plurality of electrical signals into a high sub-band signal and a low sub-band signal, the low sub-band signals from each electrical signal comprising a plurality of low sub-band signals, the high sub-band signals from each electrical signal comprising a plurality of high sub-band signals;

performing beamforming signal processing on the plurality of low sub-band signals to create a plurality of low sub-band beam signals;

combining each low-band beam signal of the plurality of low sub-band signals with the respective high sub-band signal of the plurality of high sub-band signals to create a plurality of beam signals, each beam signal of the plurality of beam signals corresponding to each microphone of the plurality of microphones of the array; and

selecting an output beam signal from the plurality of beam signals for output to an output device.