Microphone having closed cell foam body
A microphone 10 that comprises a transducer 12 and a closed cell foam body 18, 20 positioned between the transducer 12 and an opening 25 fashioned for receiving ambient sound. The microphone 10 is protected from external factors without exhibiting substantial sound transmission loss while using few parts. Good voice transmission, wind buffeting mitigation, and environmental protection can be achieved with a single material.
1. A microphone that comprises:
(a) a transducer; and
(b) a closed cell foam material positioned between the transducer and an area for receiving ambient sound, such that the closed cell foam material encloses the transducer, and the closed cell foam material is planar-shaped as positioned between the transducer and an opening of a housing through which the ambient sound passes to reach the transducer, wherein the microphone comprises the housing;
wherein the closed cell foam exhibits an insertion loss of not greater than 10 dB/mm in the 300 Hz to 3400 Hz frequency band when measured according to the Insertion Loss Test Method.
2. The microphone of claim 1 , wherein the closed cell foam exhibits an insertion loss of not greater than 6 dB/mm the 300 Hz to 3400 Hz frequency band when measured according to Insertion Loss Test Method.
3. The microphone of claim 2 , wherein the closed cell foam exhibits an insertion loss of not greater than 3 dB/mm the 300 Hz to 3400 Hz frequency band when measured according to Insertion Loss Test Method.
4. The microphone of claim 1 , further comprising:
(c) a housing into which the transducer is mounted.
5. The microphone of claim 4 , further comprising:
d) a boom attached to the housing.
6. The microphone of claim 5 , wherein the boom includes a conduit that engages the housing and that contains a wire that transmits signals from the transducer to another device.
7. The microphone of claim 6 , wherein the closed cell foam body surrounds the housing and has an opening for the boom to pass therethrough.
8. The microphone of claim 4 , wherein there is an acoustic cavity located between the transducer and the closed cell foam.
9. The microphone of claim 8 , wherein the acoustic cavity has a volume of 0.05 cm 3 to 500 cm 3 .
10. The microphone of claim 8 , wherein the closed cell foam is spaced about 0.5 mm to 50 mm from the transducer.
11. The microphone of claim 4 , wherein the closed cell foam has an average cell size of 0.1 mm 3 to 1 mm 3 .
12. The microphone of claim 4 , wherein the closed cell foam has an average cell size of 0.3 mm 3 to 0.7 mm 3 .
13. The microphone of claim 4 , wherein the foam has a density of 15 kg/m 3 to 50 kg/m 3 .
14. The microphone of claim 4 , wherein the foam has a density of 20 kg/m 3 to 40 kg/m 3 .
15. The microphone of claim 4 , wherein the foam has a thickness of 1 mm to 10 mm.
16. The microphone of claim 4 , wherein the foam has a thickness of 1.5 mm to 5 mm.
17. The microphone of claim 13 , wherein the closed cell foam comprises a polymer selected from the group consisting of ethylene vinyl acetate, polypropylene, ethylene-propylene copolymer, polyethylene, and polyvinylchloride.
18. The microphone of claim 1 , wherein a planar surface of the closed cell foam material is orthogonal to an axis, and the axis also passes orthogonally through a plane parallel with the opening of the housing.
19. A microphone that comprises:
(a) a transducer;
(b) a closed cell foam material positioned between the transducer and an area for receiving ambient sound, wherein the closed cell foam material is planar-shaped, such that the closed cell foam material encloses the transducer, the closed cell foam having a density of 15 kg/m 3 to 50 kg/m 3 and exhibits an insertion loss of not greater than 6 dB/mm in the 300 Hz to 3400 Hz frequency band when measured according to Insertion Loss Test Method;
(c) a housing into which the transducer is mounted, and the closed cell foam material is planar-shaped as positioned between the transducer and an opening of the housing through which the ambient sound passes to reach the transducer; and
(d) an acoustic cavity disposed between the closed cell foam and the transducer.
20. The microphone of claim 19 , wherein a planar surface of the closed cell foam material is orthogonal to an axis, and the axis also passes orthogonally through a plane parallel with the opening of the housing.