HIGH-FIDELITY HEARING AID-SIGNAL PROCESSING AMPLIFIER

THE ULTIMATE GOAL OF THIS RESEARCH IS TO PRODUCE A HIGH- FIDELITY HEARING AID AS PERCEIVED BY THE HEARING-IMPAIRED USER. THIS IS THE FINAL PHASE OF A RESEARCH PROGRAM STARTEDIN THE 1970S IN AN ATTEMPT TO DETERMINE THE DESIGN REQUIREMENTS FOR A HIGH-FIDELITY HEARING AID FOR WHAT SHOULDBE THE SIMPLEST CASE: INDIVIDUALS WITH A HEARING LOSS CHARACTERIZED BY A MILD TO MODERATE LOSS OF SENSITIVITY FOR QUIET SOUNDS BUT NORMAL OR NEAR-NORMAL HEARING FOR LOUD SOUNDS. AVAILABLE EVIDENCE INDICATES THAT THESE INDIVIDUALSMAY CONSTITUTE A LARGE PROPORTION OF THE HEARING IMPAIRED WHO DO NOT NOW WEAR HEARING AIDS; THUS THE MARKET FOR A SUCCESSFUL DESIGN APPEARS TO BE CONCEIVABLY GREATER THAN THEENTIRE PRESENT HEARING AID MARKET. TO DETERMINE THE PROPORTION OF NONWEARERS WHO MIGHT PURCHASE A HEARING AID IFIT INVOLVED NO AUDITORY DISADVANTAGES, A HEARING AID WITHOUTTHE CURRENT ELECTROACOUSTIC LIMITATIONS SHOULD BE MADE AVAILABLE. THE ONLY REMAINING COMPONENT NEEDED TO MAKE SUCHA HEARING AID IS A LOW DISTORTION, FOUR-STAGE COMPRESSION AMPLIFIER WITH LEVEL DEPENDENT HIGH-FREQUENCYEMPHASIS. SUCHAN AMPLIFIER, TO BE MADE AVAILABLE TO THE HEARING AID INDUSTRY, IS THE DIRECT GOAL OF THE PRESENT APPLICATION.