Insert earphones for audiometry
First Claim
1. An insert earphone apparatus including transducer means positionable away from the entrance of the human ear, and sound transmission means for transmitting sound from said transducer means to a point at the eardrum, said sound transmission means including a main sound transmission tube, first coupling means between said transducer means and one end of said tube, second coupling means at the opposite end of said tube and arranged for transmission of sound from said tube through an earpiece to said point at the eardrum, said earpiece substantially preventing exterior sounds from reaching the eardrum, and acoustic response-modifying means including damping means operative to negate the effect of resonances in said tube and to otherwise modify the acoustic response characteristic from that which would be produced by said tube and coupling means alone and thus producing a smoothly varying acoustic response characteristic, an electrical response-equalization network having an input for coupling to a signal source and an output coupled to said transducer means and having an electrical response characteristic, wherein said electrical response characteristic and said smoothly varying acoustic frequency response characteristic produce a sound pressure level at the eardrum which is a function of frequency according to one of first and second frequency response characteristics depending only upon component values in said electrical equalization network, said first frequency response characteristic being a substantially flat response characteristic, and said second frequency response characteristic being such as to closely match the diffuse-sound-field response of the normal human external ear.
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Accused Products
Abstract
Insert earphones, which are especially useful for audiometry applications include a transducer which is coupled to a resonance cancellation tube as well as to a main tube which is coupled to the ear, with series acoustic dampers in the tubes, operating in a known manner to obtain a smoothly varying frequency response characteristic. An electrical equalization network is coupled to the transducer, cooperating with the acoustic components to obtain a frequency response characteristic which is either flat or which matches that of the human ear. The dampers in series with the main and cancellation tubes have acoustic resistances which are respectively about 20% lower and 20% higher than the characteristic impedances of such tubes, operating to obtain a broadband increase in output.
100 Citations
18 Claims
- 1. An insert earphone apparatus including transducer means positionable away from the entrance of the human ear, and sound transmission means for transmitting sound from said transducer means to a point at the eardrum, said sound transmission means including a main sound transmission tube, first coupling means between said transducer means and one end of said tube, second coupling means at the opposite end of said tube and arranged for transmission of sound from said tube through an earpiece to said point at the eardrum, said earpiece substantially preventing exterior sounds from reaching the eardrum, and acoustic response-modifying means including damping means operative to negate the effect of resonances in said tube and to otherwise modify the acoustic response characteristic from that which would be produced by said tube and coupling means alone and thus producing a smoothly varying acoustic response characteristic, an electrical response-equalization network having an input for coupling to a signal source and an output coupled to said transducer means and having an electrical response characteristic, wherein said electrical response characteristic and said smoothly varying acoustic frequency response characteristic produce a sound pressure level at the eardrum which is a function of frequency according to one of first and second frequency response characteristics depending only upon component values in said electrical equalization network, said first frequency response characteristic being a substantially flat response characteristic, and said second frequency response characteristic being such as to closely match the diffuse-sound-field response of the normal human external ear.
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11. An earphone apparatus including transducer means positionable away from the entrance of the human ear and sound transmission means for transmitting sound from said transducer means to a point at the eardrum, said apparatus being arranged to operate over a frequency range extending from less than 50 Hz to more than 10,000 Hz and to produce a sound pressure level at the eardrum which is a predetermined function of frequency, said sound transmission means comprising:
- main channel means defining a narrow elongated main channel having an open entrance end and having an open exit end for positioning within the ear canal, resonance cancellation means including means defining a narrow elongated cancellation channel having an open entrance end and an opposite closed end, means defining a coupling chamber coupled to said transducer means and in closely coupled relation to said open entrance ends of said main and cancellation channels, and acoustic damper means for damping transmission in said channels, said acoustic damper means including a first acoustic damper in series with said main channel and a second acoustic damper in series with said cancellation channel, said first damper having an acoustic resistance which is approximately 20% less than the characteristic acoustic impedance of said main channel, and said second damper having an acoustic resistance which is approximately 20% greater than the characteristic acoustic impedance of said cancellation channel, in order to effect a smooth frequency response with a broadband increase in output over that obtainable with dampers whose resistances are equal to the characteristic impedances of the two said channels.
- View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
Specification