The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 19, 1988
Filed:
Aug. 14, 1986
Jorgen Heide, Cordova, TN (US);
Richards Medical Company, Memphis, TN (US);
Abstract
A noise elimination circuit, especially for a hearing aid, which removes all sound below a predetermined level and transmits a compressed sound range for all sounds above a predetermined level. The circuit uses a field effect transistor as a voltage variable resistor to transmit a signal when the sound signal is being compressed or is over a predetermined level and block the signal when the sound signal is not being compressed or is below the predetermined level. The field effect transistor drain to source resistance is varied by transmitting a signal indicative of the compression or signal level to the gate of the transistor, such that the gate voltage is higher than the source voltage when signal transfer is desired and the gate voltage is less than the source voltage when no signal transfer is desired. A switch is provided to defeat the noise elimination circuitry.