As part of the acoustic survey, we are deploying sonobuoys periodically along the track of the ship. Unlike the arrays and the CPAM which are towed behind the ship, the sonobuoys are disposable - they are not attached to the ship but dropped over the side.
Prior to deployment, a sonobuoy is programmed with specific settings such as the depth to which the hydrophone will lower, the time it will transmit data, and the radio frequency channel that it will transmit data (no need to screen the channels to avoid Italian cab drivers out here!).
In the picture you see a scientific crew member choosing these settings. Once the canister is in the water, an orange float inflates and remains on the surface. The actual hydrophone drops down to the depth that was preprogrammed. At depth, the hydrophone receives all the sounds in its vicinity. These sounds are transmitted electronically to the surface and then sent back to the ship. On the ship, we have receivers which gather the data and transfer it into visual images on the computer screen in the laboratory.
The data that we collect with these buoys focuses on the lower frequency sounds in the water, allowing us to collect more information about different species of whales, as well as ships and other ambient sounds.