Construction of an Anechoic Underwater Sound Measuring Tank
NAVY UNDERWATER SOUND LAB NEW LONDON CT
Pagination or Media Count:
The article describes a water basin with dimensions 7 m x 4 m x 4 m, which was constructed for measurements with water-borne sound. The walls of this basin are coated with absorbers effective in the frequency range from 5 to 70 kc. These broadband absorbers consist of a system of parallel, wedge-shaped rubber plates made up of three layers of rubber glued together. The center sheet is perforated with circular holes diameter 4 mm, hole density 4. There are three types of wedges differing in length 7, 15, and 20 cm covering the frequency range from 5 to 70 kc. The reflection factor related to amplitude remains below 10 in this frequency range. The excellent acoustical properties of the anechoic measuring basin are confirmed by the very small standing wave ratio for all frequencies.