ABSTRACT
Probably the most extensive investigations of outer ear acoustics were performed by E. A. G. Shaw (e.g., 1974) and his associates. My own work on the subject had a limited and practical purpose of developing a better acoustic coupler for earphone calibration. A working group of CHABA (Committee on Hearing Bioacoustics and Biomechanics of the National Research Council), which I chaired, decided that the available couplers were not entirely satisfactory and provided guidelines for the development of one that would be more up to date (Zwislocki et al., 1967). Since no laboratory picked up the challenge for a year or so and I needed a universal coupler that would allow me to calibrate various types of earphones with the same reference, I undertook the task myself. The development work extended on and off over 4 years, beginning in 1969. It required several kinds of measurements on the outer ear, which ultimately became useful in their own right. They complemented my earlier studies of the cochlea and the middle ear and helped me in accounting for the known dependence of auditory sensitivity on sound frequency. Here, I review these measurements and their analysis, which showed that the complicated geometry of the outer ear can be drastically simplified without appreciably changing its acoustic characteristics. This insight allowed me to design a coupler that lent itself to rigorous specification and was reasonably easy to manufacture.
