TPO 32.

The reading passage describes three theories that explain the possible sources of the strange sounds called 'quackers' detected by Russian submarines while patrolling the North Atlantic and the Arctic Ocean during 1960-1980. Each one of these theories is rejected by the lecturer as unlikely causes of the sounds.

The first theory presented by the reading states that those sounds were made by orca whales which the professor refutes by pointing out that orca whales live on the surface of the ocean while the submarines move around deep in the ocean, therefore, the crews could not have heard them. Besides, orca whales would have been detected by the sonar as solid moving objects, which was not the case.

The second theory in the passage claims that giant squids could have emitted the sounds. But the lecturer argues that there is a contradictory fact: the sounds started in the 1960s and ended in the 1980s whereas giant squids always have lived there and still live there, so the sounds would have continued. Thus, this theory is not plausible.

Finally, in regard to the third theory of the reading which suggests that foreign submarines were emitting those sounds inadvertently, she opposes it by explaining that the sounds changed directions quickly and by that time no submarine could move so fast. Moreover, if other submarines were the source of the sounds, then engine noise must be heard as well but no engine noise accompanied the quackers.