Listening in one language while speaking in another is among the most demanding mental tasks there is. To keep quality high, simultaneous interpreters usually work in pairs in the booth and take turns roughly every half hour. The one not speaking stays busy, jotting down numbers and names for their colleague.
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.