All the way back to the Viking age, we have made use of the sea as a road of transport and source of food, but over the past century our use of the sea has changed significantly. Human sounds in the sea come from various sources ranging from small boats, freight ships and fast ferries to oil drilling, offshore wind farms, underwater constructions, sonar and much more.
It is well known that the sounds produced by humans beneath the surface affect life in the sea. In many cases, our presence is so disturbing that animals choose to leave their territories and that it hampers social and mating behaviour; as for tooth whales their sonar is disrupted and thereby their ability to orient themselves and find food. We know that noise is a stress factor and that it affects life – both above and below the surface! We know that this is a problem, but unfortunately, documented knowledge of the effects of noise on porpoises remains limited.
At the shipyard Lillebæltsværftet, located at the harbour in Middelfart, you can follow a 180 m long underwater cable that via a hydrophone functions as our ears under the surface. This offers a unique opportunity to visit our porpoises, fish and other marine life without having to put on a diving suit and mask. Here, you can listen without disturbing the daily life and routines of the sea, and this is highly useful to researchers.
The hydrophone is a kind of underwater microphone that records all sounds within the spectrum 0-200 kHz. Through the hydrophone, we can listen not only to the animal life and ship traffic but also to wind, rain and electricity. Sound is transported better and over longer distances under water than in air, but sound can also be polluted, especially in connection with human use of the sea.
With the unique hydrophone technique, we can experience everyday life in the sea without causing disturbance and disruption to the environment.