Manipulation of playback device response using an acoustic filter

• US 9,712,912 B2
• Filed: 08/21/2015
• Issued: 07/18/2017
• Est. Priority Date: 08/21/2015
• Status: Active Grant

• Current Assignee: Sonos, Inc.
• Original Assignee: Sonos, Inc.
• Inventors: Ramos, Aurelio, Chamness, Mike
• Primary Examiner(s): Edun, Muhammad N
• Application Number:
  US14/831,903
• Publication Number:
  US 20170055066A1
• Time in Patent Office: 697 Days
• CPC Class Codes: H04R 1/2842 for loudspeaker transducers
• CPC Class Codes: H04R 1/345 for loudspeakers
• CPC Class Codes: H04R 2227/005 Audio distribution systems for home, i.e. multi-room use

Abstract

An acoustic filter includes holes and is configured to receive sound waves generated by an audio driver of a playback device. The sound waves comprise sound waves of a first frequency that radiate according to a first radiation pattern and sound waves of a second frequency that radiate according to a second radiation pattern that is less directed along an axis of the audio driver than the first radiation pattern. The second frequency is lower than the first frequency. The acoustic filter is configured to attenuate the sound waves of the first frequency so that the attenuated sound waves of the first frequency are emitted from the acoustic filter according to an effective radiation pattern that is less directed along the axis of the audio driver than the first radiation pattern and pass the sound waves of the second frequency in substantial accordance with the second radiation pattern.

Claims

1. An acoustic filter comprising:

a surface aligned with an axis extending through a transducer of a playback device; and

an array of openings in the surface, wherein individual openings define a corresponding hole in the surface, and wherein the array of openings is configured to;

receive sound waves comprising (i) sound waves of a first frequency that radiate according to a first radiation pattern and (ii) sound waves of a second frequency that radiate according to a second radiation pattern that is less directed along the axis than the first radiation pattern, and wherein the second frequency is less than the first frequency;

attenuate the sound waves of the first frequency so that the attenuated sound waves of the first frequency radiate according to a third radiation pattern that is less directed along the axis than the first radiation pattern; and

pass the sound waves of the second frequency in substantial accordance with the second radiation pattern.

2. The acoustic filter of claim 1,

wherein the sound waves of the first frequency comprise sound waves generated by the transducer that include a first set of sound waves that propagate within a first range of directions with respect to the acoustic filter,

wherein the transducer is configured to generate a second set of sound waves of the first frequency that propagate within a second range of directions with respect to the acoustic filter that is outside the first range of directions, and

wherein the array of openings is configured to allow the second set of sound waves to pass substantially unattenuated through the holes.

3. The acoustic filter of claim 2, wherein when the acoustic filter is further configured to attenuate the first set of sound waves so that the third radiation pattern is substantially equal in magnitude to the second radiation pattern over a third range of directions with respect to the acoustic filter.

4. The acoustic filter of claim 3, wherein the third range of directions includes the first range of directions.

5. The acoustic filter of claim 1, wherein the first frequency is within a range of 12-16 kilohertz (kHz) and the second frequency is within a range of 6-10 kHz.

6. The acoustic filter of claim 1, wherein the holes defined by the openings are sized to absorb the sound waves of the first frequency.

7. The acoustic filter of claim 1, wherein the array of openings includes a first opening and a second opening defining a first hole and a second hole, respectively, and wherein a center of the first hole is separated by a center of the second hole by a distance greater than 0.55 mm and less than 0.75 mm.

8. The acoustic filter of claim 1, wherein at least one of the openings has a diameter that is greater than 0.3 mm and less than 0.4 mm.

9. The acoustic filter of claim 1, wherein the surface has a thickness that is greater than 1.8 mm and less than 2.2 mm.

10. The acoustic filter of claim 1, wherein the surface has a thickness that is about equal to 2.0 mm.

11. A playback device comprising:

a transducer aligned with an axis and configured to generate (i) sound waves of a first frequency that radiate according to a first radiation pattern directed along the axis and (ii) sound waves of a second frequency that radiate according to a second radiation pattern that is less directed along the axis than the first radiation pattern, wherein the second frequency is less than the first frequency; and

an acoustic filter aligned with the axis and comprising a surface having an array of openings, wherein individual openings define a corresponding hole through the surface, and wherein the array of openings is configured to;

attenuate the sound waves of the first frequency so that the attenuated sound waves of the first frequency radiate according to a third radiation pattern that is less directed along the axis than the first radiation pattern; and

pass the sound waves of the second frequency in substantial accordance with the second radiation pattern.

12. The playback device of claim 11,

wherein the sound waves of the first frequency generated by the transducer include a first set of sound waves that propagate within a first range of directions with respect to the transducer,

wherein the transducer is further configured to generate a second set of sound waves of the first frequency that propagate within a second range of directions with respect to the transducer that is outside the first range of directions, and

wherein the array of openings is configured to allow the second set of sound waves to pass substantially unattenuated through the holes in the surface.

13. The playback device of claim 12, wherein the array of openings is further configured to attenuate the first set of sound waves so that the third radiation pattern is substantially equal in magnitude to the second radiation pattern over a third range of directions with respect to the transducer.

14. The playback device of claim 13, wherein the third range of directions includes the first range of directions.

15. The playback device of claim 11, further comprising:

an amplifier configured to amplify audio content in a range of frequencies that includes the first frequency,

wherein the transducer is configured to generate the sound waves of the first frequency based on the amplified audio content.

16. The playback device of claim 11, wherein the first frequency is within a range of 12-16 kilohertz (kHz and the second frequency is within a range of 6-10 kHz.

17. The playback device of claim 11, wherein the holes defined by the openings are sized to absorb the sound waves of the first frequency.

18. The playback device of claim 11, wherein the array of openings includes a first opening and a second opening defining a first hole and a second hole, respectively, and wherein a center of the first hole is separated by a center of the second hole by a distance greater than 0.55 mm and less than 0.75 mm.

19. The playback device of claim 11, wherein at least one of the openings has a diameter that is greater than 0.3 mm and less than 0.4 mm.

20. The playback device of claim 11, wherein the surface has a thickness that is greater than 1.8 mm and less than 2.2 mm.

21. A playback device, comprising:

an audio driver configured to generate (i) sound waves of a first frequency that radiate according to a first radiation pattern and (ii) sound waves of a second frequency that radiate according to a second radiation pattern that is less directed along an axis of the audio driver than the first radiation pattern, wherein the second frequency is lower than the first frequency, wherein the sound waves of the first frequency generated by the audio driver include a first set of sound waves that propagate within a first range of directions, and wherein the audio driver is further configured to generate a second set of sound waves of the first frequency that propagate within a second range of directions that is outside the first range of directions; and

an acoustic filter comprising holes that are configured to;

receive the sound waves of the first frequency and the sound waves of the second frequency;

attenuate the sound waves of the first frequency so that the attenuated sound waves of the first frequency are emitted from the acoustic filter according to an effective radiation pattern that is less directed along the axis of the audio driver than the first radiation pattern; and

pass the sound waves of the second frequency in substantial accordance with the second radiation pattern,

wherein the holes are positioned to allow the second set of sound waves to bypass the holes, and

wherein the holes are configured to attenuate the first set of sound waves so that the effective radiation pattern is substantially equal in magnitude to the second radiation pattern over a given range of directions.

22. The playback device of claim 21, wherein the given range of directions includes the first range of directions.