Sound Ledger¹ (Copters, Tropical Birds, Hearing Study)

Audio culture by the numbers

300,000,000: The estimated number of participants in the recent Apple Hearing study to assess sound level measurements

99: The estimated percent of birds identified by sound, not eye, in dense tropical forests

7: The increase in helicopter traffic between 2018 and 2019 in the summer months in part of Long Island, leading to a “Stop the Chop” movement


Apple: Tropical: Chop:

Originally published in the March 21, 2022, edition of the This Week in Sound email newsletter. Get it in your inbox via

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