Then there's this

Researchers in Spain have discovered that rats can distinguish human languages based on differences in cadence and intonation in speech patterns.

Rats were randomly divided into 4 groups and were rewarded after hearing either Dutch or Japanese, and eventually demonstrated that they could discriminate between a choice linked to words in Dutch and a choice linked to words in Japanese.

Before you ask, each language was spoken by the same person for each group, that is rats in all groups heard person x speaking both languages.

There are some neat tricks to the story, which you can read about here.

This is interesting because it is the first time that lower mammals have demonstrated any speech discrimination ability, and may help to validate some animal model data regarding communication disorders.