Unidirectional microphone

• US 5,692,060 A
• Filed: 05/01/1995
• Issued: 11/25/1997
• Est. Priority Date: 05/01/1995
• Status: Expired due to Fees

• Current Assignee: Knowles Electronics LLC A Delaware Limited Liability Company
• Original Assignee: Knowles Electronics Incorporated (Knowles Corporation)
• Inventors: Wickstrom, Timothy K.
• Primary Examiner(s): Kuntz, Curtis
• Assistant Examiner(s): Barnie, Rexford N.
• Application Number:
  US08/431,763
• Time in Patent Office: 939 Days
• Field of Search: 381/155, 381/168, 381/169, 381/188, 381/194, 381/195, 381/199, 381/205, 381/68-69.2, 381/68.3, 381/68.6, 181/171, 181/172, 379/430, 379/433, 379/428
• US Class Current: 381/361
• CPC Class Codes: H04R 1/342 for microphones

Abstract

A unidirectional microphone assembly for receiving sound within a range of sound frequencies is disclosed. The microphone assembly comprises a housing formed of a sound absorbing material. The housing has an outer surface, and a bore extending inwardly along a bore axis from the outer surface to form a chamber within the housing. The microphone assembly further comprises a directional microphone having an axis of maximum reception. The microphone is disposed within the chamber and positioned with its axis of maximum reception directed outwardly substantially along the bore axis.

Claims

1. A unidirectional microphone assembly for receiving sound within a range of sound frequencies, the microphone assembly comprising:

a housing formed of a sound absorbing material, said housing having an outer surface, and a bore extending inwardly along a bore axis from said outer surface to form a chamber within said housing; and

a directional microphone having an axis of maximum reception, said microphone disposed within said chamber and positioned with its axis of maximum reception directed outwardly substantially along said bore axis.

2. The microphone assembly of claim 1 wherein said bore is generally tapered from a larger outer diameter to a smaller inner diameter.

3. The microphone assembly of claim 2 wherein said taper is frustoconical.

4. The microphone assembly of claim 2 wherein said taper is stepped.

5. The microphone assembly of claim 1 wherein said taper forms an angle of substantially 120°

relative to said microphone.

6. The microphone assembly of claim 1 wherein said housing is generally cubic.

7. The microphone assembly of claim 1 wherein said housing is generally spherical.

8. The microphone assembly of claim 1 wherein said housing material is polyurethane foam.

9. The microphone assembly of claim 1 wherein said housing material is a closed cell polyurethane foam.

10. The microphone assembly of claim 1 wherein said housing material is a dense, closed cell polyurethane foam.

11. The microphone assembly of claim 10 wherein said foam has a porosity of 100 pores per inch.

12. The microphone assembly of claim 1 wherein said microphone is a super cardioid microphone.

13. The microphone assembly of claim 1 wherein said microphone is a cardioid microphone.

14. The microphone assembly of claim 1 wherein said microphone is a hypercardioid microphone.

15. The microphone assembly of claim 1 wherein said housing has a thickness of at least 1/4 wavelength of the frequencies within said range of frequencies.

16. A unidirectional microphone assembly for receiving sound within a range of sound frequencies, the microphone assembly comprising:

a housing formed exclusively of a closed cell, polyurethane foam, said housing having an outer surface, and a tapered bore extending inwardly along a bore axis from said outer surface to form a chamber within said housing; and

a cardioid-type directional microphone having an axis of maximum reception, said microphone disposed within said chamber and positioned with its axis of maximum reception directed outwardly substantially along said bore axis.

17. The microphone assembly of claim 16 wherein said taper is frustoconical.

18. The microphone assembly of claim 16 wherein said taper is stepped.

19. The microphone assembly of claim 16 wherein said taper forms an angle of substantially 120°

relative to said microphone.

20. The microphone assembly of claim 16 wherein said housing is generally cubic.

21. The microphone assembly of claim 16 wherein said housing is generally spherical.

22. The microphone assembly of claim 16 wherein said foam has a porosity of 100 pores per inch.

23. The microphone assembly of claim 16 wherein said microphone is a super cardioid microphone.

24. The microphone assembly of claim 16 wherein said microphone is a hypercardioid microphone.

25. The microphone assembly of claim 16 wherein said housing has a thickness of a approximately 1/40 wavelength of the frequencies within said range of frequencies.

26. A unidirectional microphone assembly for receiving sound within a range of sound frequencies, the microphone assembly comprising:

a generally cubic housing formed exclusively of a closed cell, polyurethane foam, said housing having an outer surface, and a tapered bore extending inwardly along a bore axis from said outer surface to form a chamber within said housing; and

a cardioid-type directional microphone having an axis of maximum reception, said microphone disposed within said chamber and positioned with its axis of maximum reception directed outwardly substantially along said bore axis.

27. The microphone assembly of claim 26 wherein said taper is frustoconical.

28. The microphone assembly of claim 26 wherein said taper is stepped.

29. The microphone assembly of claim 26 wherein said taper forms an angle of substantially 120°

relative to said microphone.

30. The microphone assembly of claim 26 wherein said foam has a porosity of 100 pores per inch.

31. The microphone assembly of claim 26 wherein said microphone is a super cardioid microphone.

32. The microphone assembly of claim 26 wherein said microphone is a hypercardioid microphone.

33. The microphone assembly of claim 26 wherein said housing has a thickness of a approximately 1/4 wavelength of the frequencies within said range of frequencies.

34. A unidirectional microphone assembly for receiving sound within a range of sound frequencies, the microphone assembly comprising:

a generally cubic housing formed exclusively of a closed cell polyurethane foam, said housing having a thickness of at least 1/4 wavelength of the frequencies within said range of frequencies, said housing having an outer surface, and a frustoconically tapered bore extending inwardly along a bore axis at an angle of substantially 120°

relative to said microphone, from said outer surface to form a chamber within said housing; and

a super-cardioid-type directional microphone having an axis of maximum reception, said microphone disposed within said chamber and positioned with its axis of maximum reception directed outwardly substantially along said bore axis.

35. The microphone assembly of claim 34 wherein said foam has a porosity of 100 pores per inch.