Ambience: room sounds, crowd, hall, footsteps
JM: If you walk into a room with your eyes closed can you figure out where you are just by listening? I’m Jim Metzner and this is the Pulse of the Planet. Our ears are actually finely-tuned instruments, working with the brain to sort and analyze the sounds all around us.
BH: I’ve always been amazed at how much information is in sound that we don’t tune into in the same way that we tune into visual information. Sound, it’s much more impressionistic.
JM: Bart Hopkin is an experimental musician in Point Reyes, California and one of the scientists and engineers in this year’s Kid Science Challenge, our free nationwide competition. He’s spent his career building musical instruments out of everyday objects, making use of our ears’ extraordinary ability to discriminate sounds.
FX: footsteps, stairway
BH: It’s amazing how much sound information we process without thinking about it. And so, first of all, you could say, “How did I know somebody was at the door? Oh. I guess I heard them walking up the steps.” That’s one level, but another level you could say is, “What information about the oscillations in the air that reach my ears even made me know that that was somebody coming up the steps?”
FX: footsteps, high heels
JM: So if you hear the high-pitched click of high heels, you may just know who’s walking down the hall. Or when you listen to the sound of my voice you know I’m inside a room, not outside on a mountaintop.
FX: crowded room, echoey room
BH: That as I speak, the sound is reflecting off of other interior surfaces and there are things about how long those reflections take. Do they arrive almost immediately, or do they take a while to arrive? That tells you a little bit about how big or how small the room is. do they favor high frequencies or low frequencies? That tells you a lot about whether you’re in a room with a lot of people or a lot of soft furniture versus a room that is cavernous with hard walls.
BH: We do somesome pretty serious analysis.
JM: In this year’s Kid Science Challenge, we’re inviting 3rd to 6th graders to do some sound analysis of their own by coming up with an idea for a new musical instrument. Check out Kid Science Challenge.com. Pulse of the Planet is made possible by the National Science Foundation.