The photophone—physical design
D. A. Kleinman, D. F. Nelson · The Journal of the Acoustical Society of America · 1976
The physical design of the response-equalizing components of the acoustic transformer-coupled photophone is presented. Two possible equalizers for the absorption cell—a gas column and a loaded diaphragm— are discussed; one equalizer for the earpiece, consisting of a diaphragm and screen, is also discussed. The optimization, equalization, and physical realization of a direct-coupled photophone (one not containing an exponentially tapered tube acting as an acoustic transformer) is also presented. It is found that its response is poorer than the transformer-coupled photophone by 25 dB. Subject Classification: [43]85.86, [43]85.40, [43]85.60.