No abstract

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.

The construction and operation of a high resolution interferometer for solar noise observations at 10.7 cm for the Algonquin Radio Observatory is described. One element is the existing 32 element array of 3 m reflectors while the second is a grating dement of 4 reflectors symmetrically placed on the same E-W line. The aperture of 665 m produces a fan beam of 0.5' E.W. by 2 ~ N.S. Four Faraday rotators in the antenna feeds of the newly commissioned grating enable three Stoke's parameters to be observed. The expected antenna pattern is confirmed by making observations on the brighter radio sources. Observations of the Sun on 1972, January 6 show the range of phenomena to be observed and a detailed study of the association of eight radio emissive regions with all centers of solar activity is presented.

Sound-pressure recordings made in real-ear simulators are more realistic than those made in 2-cc couplers. Unfortunately, most real-ear simulators (1) require factory calibration and (2) were designed to simulate only the mean acoustic impedance of normal adult ears. Due to variability of ear-canal geometry and eardrum impedance among subjects, the statistical possibility of any one subject exhibiting such “mean” characteristics—especially if that subject has a conductive pathology—is very remote. Reported herein is the development of a programmable artificial ear (PAE) which (1) requires no factory calibration and (2) can be programmed to account for individual variations in source impedance, ear-canal geometry, and eardrum impedance. The PAE consists of a 2-cc coupler, microphone, amplifier, and desk-top scientific computer, equipment which is included in most laboratory/clinic inventories. Sound pressures recorded in the 2-cc coupler are adjusted via the computer to what they would have been had the recordings been made in a particular subject's ear. Good agreement has been obtained between PAE data and real-ear simulator measurements.