Rotokas, spoken in Papua New Guinea, has one of the smallest sound inventories known: about six consonants and five vowels. At the other extreme, Taa (or !Xóõ) of Botswana, rich in clicks, has over a hundred distinct sounds by some analyses. English, with around 40 phonemes depending on accent, sits a little above the global average.
In Kuşköy, a mountain village in northern Turkey, people talk across valleys by whistling Turkish. A 2015 study showed that whistled Turkish draws on both hemispheres fairly evenly, whereas spoken Turkish relies mostly on the left. The physical form of the signal, it turns out, matters to the brain.
Speech has no gaps between words. In 1996, researchers played 8-month-old babies a continuous stream of made-up syllables for just two minutes. The infants picked out the 'words' by tracking which syllables tend to follow one another. That's probability calculation, done without a calculator or any visible effort.