US3763333A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Acoustic feedback stabilization system particularly suited for hearing aids
Assignee: AMBITEX Co
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Filing: 1972-07-24
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Granted: 1973-10-02
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Expires: 1992-07-24
Abstract
Abstract Linearity is increased and distortion reduced in a miniature acoustic amplifying system by providing an acoustically communicating passage between the microphone and speaker diaphragms to define a negative acoustic feedback loop for the amplifying system. The negative acoustic feedback is feasible because of the miniature arrangement itself of the microphone and speaker wherein the distance of the acoustic passage can be made a small fraction of the wave length of the highest frequency in a given frequency range to be amplified. An adjustment is provided for changing the acoustic coupling between the microphone and speaker diaphragms to thereby adjust the negative feedback loop. This adjustment can also serve as a volume control and the entire system is highly suitable for use in hearing aids wherein miniature microphones and speakers are utilized in close physical proximity.
Inventors
- 👤 A Lichowsky
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 12:15
CPC Classifications
H; H04; H04R; H04R25/00; H04R25/45; H04R25/453; H04R3/00; H04R3/002
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
87 words
A method of increasing linearity and reducing signal distortion over a given frequency range in a miniature acoustic amplifying system comprised of a microphone, amplifier and speaker, including the steps of: a. providing an acoustically communicating passage between the responsive diaphragms for the microphone and speaker of length less than one quarter of the signal wave length of the highest frequency in said range; and b. varying the degree of acoustic coupling between the diaphragms to provide an adjustable negative acoustic feedback loop for said amplifying system.
Claim 2
Independent Claim
87 words
A method of increasing linearity and reducing signal distortion over a given frequency range in a miniature acoustic amplifying system comprised of a microphone, amplifier and speaker, including the steps of: a. providing an acoustically communicating passage between the responsive diaphragms for the microphone and speaker of length less than one quarter of the signal wave length of the highest frequency in said range; and b. varying the degree of acoustic coupling between the diaphragms to provide an adjustable negative acoustic feedback loop for said amplifying system.
Claim 3
Dependent Claim
58 words
The method of claim 1, including the step of providing an electronic negative feedback loop around said amplifier having its response adjusted to compensate for the response of the microphone and the speaker to thereby control the overall amplifier gain roll-off characteristics and permit stable closed-loop operation with a substantial amount of said negative acoustic feedback taking place.
Claim 4
Dependent Claim
102 words
A miniature acoustic amplifying system having a microphone, amplifier and speaker and including: a. an enclosure for the microphone and speaker diaphragms, a portion of said enclosure defining an acoustically communicating passage between the diaphragms of length substantially less than the wave length of the highest frequency in a contemplated signal frequency range to be amplified to thereby provide acoustic coupling between the microphone and speaker; and b. means in said passage for attenuating the acoustic coupling through said passage in a controlled manner whereby a negative acoustic feedback loop is provided for said amplifying system to increase linearity and reduce distortion.
Claim 5
Dependent Claim
102 words
A miniature acoustic amplifying system having a microphone, amplifier and speaker and including: a. an enclosure for the microphone and speaker diaphragms, a portion of said enclosure defining an acoustically communicating passage between the diaphragms of length substantially less than the wave length of the highest frequency in a contemplated signal frequency range to be amplified to thereby provide acoustic coupling between the microphone and speaker; and b. means in said passage for attenuating the acoustic coupling through said passage in a controlled manner whereby a negative acoustic feedback loop is provided for said amplifying system to increase linearity and reduce distortion.
Claim 6
Dependent Claim
51 words
A system according to claim 3, in which said amplifier includes an electronic negative feedback loop adjusted to provide a frequency response characteristic which compensates for the response characteristics of the microphone and speaker to permit stable closed loop operation with a substantial amount of said negative acoustic feedback taking Place.
Claim 7
Dependent Claim
123 words
A system according to claim 3, in which said enclosure is dimensioned and shaped to fit a person''s ear, and includes an input acoustic passage communicating with said microphone and an output acoustic passage communicating with said speaker, said acoustically communicating passage extending between the input and output passages; and in which said means in said passage for attenuating the acoustic coupling includes a threaded member extending partially into a side of the passage and accessible from the exterior of said enclosure for threaded adjustment whereby the effective cross-sectional area of the passage is adjustable by the degree of threading of the member into the passage, so that a hearing aid is provided in which the volume can be adjusted by said member.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-10-01 | 1977-04-02 | 1977-10-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-01 | 1981-04-02 | 1981-10-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-01 | 1985-04-02 | 1985-10-02 | $7700.00 | Window Closed / Lapsed |