Noisy oceans

Sound is known to travel at 343 m/s through air, but if it travels through different materials this speed changes. For example through water the speed is 1480 m/s. If we connect this physical fact with the rise of maritime trade, we'll have the explanation of the gaining noise pollution in oceans.


It could be very dangerous because marine mammals communicate using impulsive signals called clicks, emitted between  500 Hz and 30 kHz, and the background noise generated by humans could interfere with them. Low frequency noise can also damage vital organs of several cephalopod.

One way to avoid those problems could be building solid barriers around either the source of the noise or the area to protect. Nevertheless it could result to be very expensive, and so others options are being proposed. The most innovative one forecasts the use of bubbles.

The problem is mainly related to the fact that low frequency waves are characterized by long wavelengths. You would need at least 10 cm bubbles to reduce significantly the noise. Furthermore those bubble should not break in smaller ones, so latex capsules are needed. Test performed on these kind of bubbles shown that they would reduce noise by 44 decibels.


Even though this reduction is significant (it's the difference between a library and a busy street), it's not enough. The noise travelling though water would  be in fact reduced, but the one transmitted by seabed would not. So further solution are needed: only reducing the amount of noise pollution in oceans problems such as marine mammals strands could be reduced.