Outside of a library in Cambridge, Massachusetts, an over-80-year-old copper beech tree is making music. As the tree photosynthesizes and absorbs and evaporates water, a solar-powered sensor attached to a leaf measures the micro voltage of all that invisible activity. Sound designer and musician Skooby Laposky assigned a key and note range to those changes in this electric activity, turning the tree's everyday biological processes into an ethereal song. That music is available on Hidden Life Radio, an art project by Laposky. Hidden Life Radio also features the musical sounds of two other Cambridge trees: a honey locust and a red oak. After he read the book The Hidden Life of Trees ... Laposky thought to tune into the music trees could be making. The name Hidden Life Radio was inspired by that book, written by German forester Peter Wohlleben, which details the social networks and "sentient" capabilities of trees. "Most people probably love trees and [still] don't consider them all the time," Laposky says, noting a condition called "plant blindness," in which people fail to notice the flora in their own environment. "In cities, the trees are there, but unless they're providing shade or you're picking apples from them, I feel like people don't necessarily consider trees and their importance." Tree canopies are crucial to cities, providing shade that can lower summer temperatures significantly, reducing air pollution, sequestering carbon, and providing a mental health benefit.