A headphone that is especially useful to test the efficacy of an earplug installed in an ear canal, by using the headphone to produce sound and by sensing sound pressure at the ear drum despite the presence of the earplug. Applicant uses the speaker ( 42 ) in the headphone to produce a smooth and reasonably “flat” frequency response by reversing the speaker orientation. In the reversed orientation, the front side of the speaker diaphragm ( 50 ) faces into the headphone cup and away from the ear. The rear side of the speaker that has a circle of holes ( 52 ), faces toward the ear. The headphone frame has a cylindrical passage ( 40 ) for carrying sound to the person's ear, which has an outer end ( 78 ) that is tapered to encompass the holes in the speaker back side ( 44 ). The axial distance (L) from the speaker rear side to the ear, is at least 0.6 inch to accommodate the protruding end of an earplug.
1. A headphone which includes a frame that forms a frame passage, a cushion mounted on an inner end of said frame for pressing against a location on a person that lies around the person's ear canal, said frame has an outer wall that blocks sound, and said headphone has a speaker that lies in said frame and that has a speaker diaphragm side comprising a diaphragm that vibrates inward and outward to generate sound and an opposite speaker hole side that forms a second wall with a plurality of holes, wherein:
said speaker is mounted with said speaker second wall that has holes facing inwardly toward the person's ear canal and with said holes opening to said frame passage, and with said speaker diaphragm side that comprises a diaphragm, facing outwardly away from the person's ear canal;
the frame further comprising a rigid tube that forms the frame passage extending from the cushion to the speaker, wherein the rigid tube is located on a central axis of the frame;
wherein the rigid tube has a constant diameter for most of its length, but has a speaker end tapered in diameter to have progressively smaller diameters at progressively more inward locations therealong; and wherein the holes in the speaker second wall lie within a hole circle and the tapered speaker end of the tube has an outward end diameter at least as great as the hole circle.
2. The headphone described in claim 1 wherein:
the rigid tube has an inside of a diameter of not more than 1.5 inches along most of its length which extends from said speaker second wall that has holes to the inner end of said headphone, whereby to direct sound toward a person's ear canal.
3. The headphone described in claim 2 wherein:
said tube has a length, from said speaker second wall that has holes to an outer end of said cushion, of at least 0.5 inch.
4. The headphone described in claim 1 wherein:
said tube has a length, from said sneaker second a that has holes to an outer end of said cushion, of at least 0.5 inch.
5. The headphone described in claim 1 further comprising a sound absorbent foam located between the speaker diaphragm side and the frame outer wall.
6. The headphone described in claim 5 ;
wherein the tube has an inside diameter of not more than 1.5 inches along most of its length from the cushion to an inward end of the tapered speaker end; and
wherein the tube has a length, from said speaker second wall to an outer end of said cushion, of at least 0.5 inch.
7. A headphone which includes a frame with a central axis, a cushion at the front end of said frame for pressing against a side of person's head around the ear canal and, with a rear end that is closed to block the passage of sound, with a passage extending along said central axis, and with a speaker lying at a rear end of said passage, wherein:
said headphone includes a rigid tube that forms said passage and that extends from a rear end of said cushion to said speaker, said rigid tube having an inside diameter of not more than 30 millimeters;
said speaker has a first side that has a wall with a plurality of holes and an opposite second side with a diaphragm thereat, said first facing forwardly towards the person's ear canal and said holes opening to a rear end of said rigid tube; and
the rigid tube has a constant diameter for most of its length, but has a speaker end tapered in diameter to have progressively smaller diameters at progressively more inward locations therealong; and wherein the holes in the speaker first side wall lie within a hole circle and the tapered speaker end of the tube has an outward end diameter at least as great as the hole circle.
8. The headphone described in claim 7 , wherein:
said rigid tube has a length of at least 0.5 inch.
9. The headphone described in claim 7 further comprising a sound absorbent foam located between the second diaphragm side of the speaker and the frame rear end.
10. A headphone which includes a frame with a central axis, a cushion at the front end of said frame for pressing against a side of person's head around the ear canal and, with a rear end that is closed to block the passage of sound, with a passage extending along said central axis, and with a speaker lying at a rear end of said passage, wherein:
said headphone includes a rigid tube that forms said passage and that extends from a rear end of said cushion to said speaker, said rigid tube having a length of at least 0.5 inch;
said speaker has a first side that has a wall with a plurality of holes and an opposite second side with a diaphragm thereat, said first side facing forwardly towards the person's ear canal and said holes opening to a rear end of said rigid tube; and
the rigid tube has a constant diameter for most of its length, but has a speaker end tapered in diameter to have progressively smaller diameters at progressively more inward locations therealong; and wherein the holes in the speaker first side wall lie within a hole circle and the tapered speaker end of the tube has an outward end diameter at least as great as the hole circle.
11. The headphone described in claim 10 , wherein:
said rigid tube has a length of at least 0.6 inch.
12. The headphone described in claim 11 wherein the tube has an inside diameter of not more than 1.5 inches along most of its length from the cushion to an inward end of the tapered speaker end.
13. The headphone described in claim 10 wherein the tube has an inside diameter of not more than 1.5 inches along most of its length.
14. The headphone described in claim 10 further comprising a sound absorbent foam located between the second diaphragm side of the speaker and the frame rear end.