Occluded-ear simulator with variable acoustic properties.
Ear simulators were designed to replicate acoustical characteristics of the average adult ear. Due to variability of ear-canal geometry and eardrum impedance among individuals, the possibility of any one person exhibiting such "average" characteristics--especially if that person is a child and/or has a conductive pathology--is remote. Thus, ear simulators have been of only peripheral value when prescribing a hearing aid (a high output impedance device) to fit the acoustical requirements of a particular patient. Reported herein is development of a programmable artificial ear (PAE) that can account for individual differences in ear-canal geometry and eardrum impedance. It consists of a 2.0-cc coupler, microphone, amplifier, computer, PAE code, and a computer card and/or software for digitization and Fourier transformation. Required input data includes ear-canal dimensions, eardrum impedance, and output impedance of the hearing aid being tested. Sound-pressure recordings produced in the 2.0-cc coupler by the hearing aid are adjusted by the computer to what they would have been had the recordings been made at the eardrum of a particular patient wearing the same hearing aid. Good agreement was observed between experiment and theory for one test case involving a totally occluding miniature earphone.
Egolf
D P
DP
Audiology Research Program, V.A. Medical Center, Augusta, Georgia 30910.
Kennedy
W A
WA
Larson
V D
VD
D000158:Acoustic Impedance Tests; D000162:Acoustics; D004423:Ear / Q000502:physiology*; D004424:Ear Canal / Q000502:physiology; D004582:Electronics, Medical; D006310:Hearing Aids; D006801:Humans; D008422:Materials Testing; D008954:Models, Biological; D011312:Pressure; D012815:Signal Processing, Computer-Assisted; D012984:Software; D013016:Sound