This summer we were lucky enough to be given a hydrophone to test and use. The hydrophone was provided by Seiche. Seiche is an innovative company based in North Devon working mainly in the area of passive acoustic monitoring and they offer training, consultancy and project work. Passive acoustic monitoring involves listening for cetaceans in order to protect them from noisy operations in the ocean such as oil and gas surveying with seismic cannons. They also produce hydrophones and recently developed the LSTN2 hydrophone, which is ideal for eco-tourism operators.
The LSTN2 hydrophone is designed to be easy to use – and it is! It uses auto-tuning, which means it tunes in to the sounds it detects. It can be used with headphones, a speaker or even a laptop or tablet. It has two output jacks so it’s possible to plug it in to headphones, or a speaker and a tablet/laptop at the same time. This allows you to listen to the sounds whilst viewing the output spectrogram. The spectrogram output can be recorded for later analysis and this feature makes it suitable for research as well. The hydrophone comes with a 10 metre cable, a control case, connecting cables and a bag. It’s well made and robust enough to stand up to daily use.
We have used the hydrophone when conditions are suitable all summer and have achieved some spectacular results. Using it with a small mobile speaker (cost £10 ) allowed us to share the output with the whole boat. Initially it took a little time to get used to using it. We only had limited experience using hydrophones, however the ease of the LSTN2 helped us to quickly achieve good results. An early lesson we learned was that the deeper the hydrophone the better, so the 10 metre cable is a real plus point because it allows the hydrophone to be deployed to an optimum depth. We did find that if it was windy the boat would drift, dragging the hydrophone towards the surface and reducing it’s effectiveness. Next year I’m planning on weighting it in order that it stays deep even when the boat is drifting.
If the animals being listened to are moving around a lot and covering large distances it can also be tricky. However when deployed in good conditions it produces brilliant results and has added another level to our dolphin encounters. Passengers have really enjoyed listening to the animals surrounding the boat.
The auto-tune picks up all the noises in the ocean and that includes boats. You’d be amazed at how far noise carries and how noisy even small motor boats are! We found that boat noise tends to overpower the cetacean noises being detected. While the boats spoil our listening experience, it can also provide a great education tool. It highlights the problems of ocean noise pollution and raises the awareness of our passengers to this growing problem.
We have really enjoyed using the LSTN2 in 2016, and it has enhanced the experience of our passengers. Each time we deploy it we seem to detect something new. Have a watch/listen to the embedded videos to see what I mean. I remember one occasion when we were watching and listening to a pair of dolphins swimming around the boat. We became aware that the two common dolphins were making a lot of noise for their small number. We kept listening and watching only to be ambushed by 50 more common dolphins that had sneaked up on us. The racket coming out of the hydrophone suddenly made sense. My next goal is to listen to harbour porpoises with the LSTN2. I’m just waiting for a calm day!
If you get out and about on the water whether it be running trips or purely for your own recreation then I wholeheartedly recommend the LSTN2. It’s not only great for listening to cetaceans but can also detect a host of other marine species, and it will enhance your experience of the marine environment.