Underwater speaker

We use an underwater speaker (intended for synchronized swimmers) to measure how sound propagates in different environments. The Lubell system (model 9816, akin to the caged [LL916C projector http://www.lubell.com/LL916.html] has a maximum output level of 180 dB re 1 microPa @ 1 m for a 1 kHz tone. 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.