XLI. Acoustic Filtering

A technical statement of the action of such resonators appears in the April number of the Physical Review.

(1) “Acoustic Wave Filters,” Stewart G. W. . Phys. Rev., Vol. XX, No. 6, December, 1922. (2) “A Variable Single Band Acoustic Wave Filter,” Stewart G. W. . Phys. Rev., pp. 502–505, No. 5, November, 1923. (3) “Predicted Transmission Curves of Acoustic Wave Filters,” Peacock H. B. . Phys. Rev., pp. 525–527, No. 4, April, 1924. (4) “Acoustic Wave Filters: Attenuation and Phase Factors,” Stewart G. W. . Phys. Rev., pp. 520–524, No. 4, April, 1924. (5) “Acoustic Wave Filters in Series,” Stewart G. W. , Jour. of Optical Society of America, Vol. 9, No. 5, November, 1924. (6) “Acoustic Wave Filters; An Extension of the Theory,” Stewart G. W. . Physical Rev., pp. 90-98, No. 1, January, 1925.

The technical papers, to which reference has been made, show that it is possible to compute the performance of these filters. Unfortunately the application of the theory is too complicated for reduction to specific directions.

Curve D would give 100 per cent at 5,000 vibrations, were it not for the viscosity introduced by a number of small holes. In practice, these holes are not usually small and this experimental effect is not common.