Yes, dolphins talk. Their inter-species communication is much more complex than initially believed with sentences that can reach up to five words long and a language that's actually not too far from human conversations.

It has long been established that dolphins can communicate with each other, but the extent has not been clear. According to a report from Telegraph, researchers developed an underwater microphone to study the depth of communication of the intelligent creatures, a tool that was able to distinguish the dolphins' different "voices".

The scientists from Karadag Nature Reserve in Feodosia, Russia discovered that the mammals create individual "words" by altering the volume and frequency of their traditional pulsed clicks.

The team studied two Black Sea bottlenose dolphins in particular: Yasha and Yana. Both in a pool, one of the pair would listen to a sentence without interruption to the other before responding with a string of words as well. Their exchanges would reach up to five words.

"Each pulse that is produced by dolphins is different from another by its appearance in the time domain and by the set of spectral components in the frequency domain," Dr Vyacheslav Ryabov, lead researcher, explained. "In this regard, we can assume that each pulse represents a phoneme or a word of the dolphin's spoken language. The analysis of numerous pulses registered in our experiments showed that the dolphins took turns in producing [sentences] and did not interrupt each other, which gives reason to believe that each of the dolphins listened to the other's pulses before producing its own."

He concluded, "This language exhibits all the design features present in the human spoken language, this indicates a high level of intelligence and consciousness in dolphins, and their language can be ostensibly considered a highly developed spoken language, akin to the human language."

The next step for humans is finding out how to communicate directly with dolphins. As of now, the content of the creatures' conversations is still unknown.

The study is published in the St. Petersburg Polytechnical University Journal: Physics and Mathematics, available online on Science Direct.