SINGING UNDERWATER When we are asked to name an animal which can sing, we right away think of birds. And if you are a good singer, people would say that you sing like one. But why no one says 'you sing like a whale'? Well, we hear birds singing every day, while not everybody is able to go underwater or is reckless enough to get close to a whale. Those who do, are biologists and marine life researchers trying to understand these animals' behavior, and the way they communicate with each other, which they do by singing. Besides, I doubt there is a human who can sing like a blue whale since they do it within a register similar to 'the lowest, longest pipes of large cathedral organs.' In this case, 'you sing like a whale' maybe would not be a very good compliment. When humans sing, the pitch they use sometimes has to do with the feeling they want to express. Generally, low tones are sadder than high tones. We may not expect blue whales to know the difference, but for some reason, their pitch has been changing for the last decades, and the reason why it is happening still cannot be completely explained. Blue whales, more specifically males, can sing very loud. The frequency of their sounds can travel more than 1,000 km. The pitch of these sounds is dropping, apparently because they are singing less loudly. The most accepted explanation is that whales are not needing to sing louder to find other whales due to a rebounding population. Also, how fast and far sound can go underwater depends on the temperature, pressure and chemistry conditions. The more acid is the water the further the sound will go. As climate change is acidifying the oceans, this is contributing to whales not having to be so loud. There are other conditions which also affect the intensity of their calls. The amount of noise from their surroundings is an important one. That is why during summer, when icebergs start breaking causing a lot of noise, they have to sing louder to hear each other, and this makes their pitch go up a little. But this is something that occurs in a short-term, during a specific season, and as a consequence of having to sing louder. The long-term tendency is a lowering of their pitch at 0.14 hertz (Hz) per year. Humans can hear from 20 Hz to 20,000 Hz, and whales' songs have a frequency of typically 15 to 30 hertz, so their sounds are at the bottom edge of our audition capacity. If this continues, perhaps someday we won't be able to hear them.