Results of underwater ambient noise measurements in three large tank exhibits at the Monterey Bay Aquarium

Abstract

Measurements have been made of the underwater ambient noise in three large tank exhibits at the Monterey Bay Aquarium: the Kelp Forest Exhibit (335 000 gal), the Monterey Bay Habitats Exhibit (350 000 gal), and the Outer Bay Waters Exhibit (1.4 million gal). A single, calibrated, Navy-type DT-276 was used. The hydrophone output voltage was preamplified and recorded using a 16-bit digital audio tape recorder with a sampling rate of 48 kHz. Measurements were made with various mechanical equipment (motors, fans, pumps, sprinklers, wave machine) turned on and off. On one occasion, the noise was measured in the largest tank, the Outer Bay Waters Exhibit, during a power shutdown. For comparison, measurements were also made at several locations and depths in the inner Monterey Bay. The results of one-third octave band and narrow-band analyses will be presented. Comparisons will be made between the aquarium and bay results and standard deep water ambient noise spectral density curves.