Abstract
Normal incidence coefficients were measured by means of standing waves in a heavy brass tube 1012 inches in diameter and 7 feet 4 inches long. Both ends of the tube were carefully sealed to prevent leakage, and the sample was not removed during the course of a set of measurements on a given material. A selective amplifier of the degenerative feed-back type was used to eliminate any possible effect due to variation of harmonic content with intensity. Measurements were taken on a wide selection of materials over a range of 30 to 40 decibels. Any variation in the value of the absorption coefficient due to change in the intensity of sound was not more than 1.5 percent.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
