Electronic filters, signal conversion apparatus, hearing aids and methods
US5357251A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 30, 1993 |
| Grant date | Oct 18, 1994 |
| Priority date | — |
| Expiry date | Apr 30, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04R25/505
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An electronic filter for filtering an electrical signal. Signal processing circuitry therein includes a logarithmic filter having a series of filter stages with inputs and outputs in cascade and respective circuits associated with the filter stages for storing electrical representations of filter parameters. The filter stages include circuits for respectively adding the electrical representations of the filter parameters to the electrical signal to be filtered thereby producing a set of filter sum signals. At least one of the filter stages includes circuitry for producing a filter signal in substantially logarithmic form at its output by combining a filter sum signal for that filter stage with a signal from an output of another filter stage. The signal processing circuitry produces an intermediate output signal, and a multiplexer connected to the signal processing circuit multiplexes the intermediate output signal with the electrical signal to be filtered so that the logarithmic filter operates as both a logarithmic prefilter and a logarithmic postfilter. Other electronic filters, signal conversion apparatus, electroacoustic systems, hearing aids and methods are also disclosed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.