Underwater speaker

From Beam Reach Wiki

We use an underwater speaker (intended for synchronized swimmers) to measure how sound propagates in different environments. The Lubell system has a maximum output level of 180 dB re 1 microPa @ 1 m. In spreading lab exercises off the Friday Harbor Lab docks, we have measured source levels of about 160 - 170 dB re 1 microPa @ 1 m with a typical sound sample and gain settings.