For a more enjoyable calling experience it also uses age-specific frequency adjustment and real-time speech slowing to help make calls crystal clear.

CNN: The mobile device that thinks it's a Russian doll

Though these changes can go unnoticed by a person with a disease, relatives and friends more often pick up on it, but a computer algorithm that detects nuances of speech and subtle changes could detect abberations with much greater frequency.

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If you were to look at a waveform where you see how speech gets louder and quieter across time, the time between those peaks happens at a fairly predictable frequency of 3Hz to 8Hz across different languages.

BBC: Primate call gives clues to human speech origins