TPO 56

The passage provides us with three possible explanation for 52-hertz whale's unique high-pitched song while the professor has enough reasons to reject all those theories, and he believes that its high-pitched song remains a mystery for scientists.
The first hypothesis is that this type of whale may be a combination of two different whale species, which has a unique song. In stark contrast, the lecturer thinks that their migration patterns demonstrate that this theory cannot be true since they unusually migrate alone while other known hybrid whale migrate in different patterns. So, this cannot be a great reason for 52-hertz whales' unique high-frequency song as a hybrid offspring.
The damage sense of hearing like something which may happen for human is considered as the second theory. Whereas, the professor supposes that this high-pitched song is related to the physical structure of their throats, which means their vocal apparatus should have a specific character which let them make this sort of song. As a result, there is no connection between this song and the damage of hearing sense.
The last explanation is that it is likely that the 52-hertz whale is the only member of a rare species. Conversely, the professor thinks that this whale has to have parent, and scientists have had the technology to receive whales' sound for many decades. Therefore, some song like that should have been recorded. Thereby, there is no convincing evidence for such a thing, and this theory has failed totally.
In brief, although the reading presents some reasons for that high-pitched song, the lecturer refutes all of them and believes that they are not complete.