240,000,000: Estimated number of years since when male katydids have made sounds by rubbing their wings
60: Number of dust grain impacts per second recorded by the Mars rover
30: The percent that the measured frequency of whale songs has declined over the past four decades
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¹Footnotes
Katydid: [newscientist.com](https://www.newscientist.com/article/2351116-fossils-reveal-the-dinosaur-eras-changing-insect-soundscape/). Mars: [newscientist.com](https://www.newscientist.com/article/2351154-nasas-perseverance-rover-recorded-the-sound-of-a-dust-devil-on-mars/). Whales: [nautil.us](https://nautil.us/the-mystery-of-the-blue-whale-songs-248099/).