In 1886, linguist Paul Passy founded an association of language teachers in Paris. Two years later, it published the International Phonetic Alphabet (IPA), built on a simple principle: one symbol per sound, whatever the language. So French 'ch', English 'sh' and German 'sch' are all written [ʃ]. Regularly updated, the IPA now has more than a hundred letters, used in dictionaries worldwide.
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.