What is a soundscape? Let’s say you step outside your house, a plane flies over head, 5 o’clock traffic is happening down the road, a nice breeze sweeps by and rustles the trees, and your neighbor’s kids are playing with the sprinkler in their front yard — all these sounds coming in and hitting your ear create a “soundscape”.
The combined sounds, that vary in loudness, duration and pitch compose the soundscape for that area. If we were to take the above scenario and put it underwater, all the sounds you hear would be louder, and you perhaps would even hear additional sounds. Sound travels 4.5x faster and travels much further underwater than in air! So, while you may have missed the whispering neighbors at the far end of your street above water, you may now be hearing the gossip below water.
So, what does the ocean sound like? Below gives us a snapshot of different sounds that occur:
Marine mammals use acoustic sounds to communicate with one another. As the background noise of the ocean has drastically increased over the years, scientists have become concerned about potential “masking” of marine mammal acoustic communication.
The above figure demonstrates examples of soundscape data taken offshore at Newfoundland, Canada. The figure (B) shows the loudness of different frequencies recorded in the area. Circled are the frequency and timescale ranges for of 3 different sources: dynamic positioning vessel, seismic survey, and fin whale songs. Notice that the noise of the seismic surveys overlaps with fin whale songs.
Not only do some anthropogenic (human-made) sounds fall in the same frequency ranges these animals communicate at, but they are also very loud. Imagine being at a rock concert and trying to talk with your friend. You probably have to shout or get really close; you may even choose to say fewer words because communicating with your voice is not efficient. Your friend may not even understand the words you are saying and ask you to repeat. You may just switch to hand signals or just choose not to communicate until the music stops. Scientists believe marine mammals may be facing similar decisions when trying to communicate to their group members during noisy events.
Marine mammals have been reported to change the frequency and/or duration of their calls – sometimes ceasing all communication – when they are in the presence of loud anthropogenic noise. This can lead to serious impacts:
- exerting extra energy to try and send audible calls
- missing important calls that may indicate food or a mate
- temporary or permanent shifts in behavior
- temporary or permanent avoidance or relocation
It is important for scientists, decision-makers, boaters and even recreational swimmers to continue to work together to reduce the noise we impart into the ocean. Remember it is louder and travels much further than you may think, so we must keep in mind the animal’s perspective and allow them to live out their natural behaviors as best as possible.
For additional information on soundscapes and research click here.