The effectionately-called 'Shark of Science' is a multiple hydrophone array with 16 hydrophones
on a mooring rising up from the bottom and 32 more hydrophones laying in a line along the ocean
bottom in a north-south direction. During an experiment 100 miles off the coast of New Jersey we
picked up these sei whale vocalizations. We know they were sei whales since the sounds we picked
are within the 40-100Hz frequency band, modulate from the highest frequency to the lowest, and
typically come in pairs (see spectrogram below). We can use this data to track the whales.

The image below gives you an idea of the size of a Sei whale. For more sei whale information,
check out Wikipedia. Also, see how gliders monitor marine mammals here at WHOI.

Below is a spectrogram made from one of our recordings which shows 2 seiwhale vocalizations
modulating from ~100Hz to ~40Hz. Click on the image to get a better look.

Play Sei Whale sound (Because the frequencies are so low, you may need a subwoofer to hear it!!)