In this episode, we're answering your questions about...us! Why do you make But Why? How are podcasts made? And we're answering questions about the physics of sound and radio.
What is sound and how is it made? Why are sound waves invisible? How do echoes work? How do microphones work? How do radio signals work? Answers to your sound and radio questions from our VPR colleagues: sound engineer Chris Albertine and Chief Technology Officer Joe Tymecki.
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"What is sound made of and how is it made?" - Eli, 8, Boulder, CO
Sound engineer Chris Albertine offers some ways to think about sound: "When something vibrates, it makes sound. Think of a guitar string or a harp, that's the easiest thing to imagine. When you pluck one of those things you vibrate the air molecules, those molecules go out into the air and hit your ear drums. Your ear drums vibrate back and forth and your brain interprets what it sounds like."
So to make sound there's something vibrating the air, like a guitar string moving back and forth. But you also need a receptor, like your ears, to interpret that sound.
"If you look at a speaker, watch it bounce in and out. It's pushing air out into the atmosphere. Your ear drum is working the same way interpreting that sound." And then your brain interprets the signals to understand what sound you are hearing.
We can't see sound waves because we can't see the air molecules they move through. But you can picture how those sound waves move through the air like the ripples in water made when you drop a rock into a pond.
"How are podcasts made? - Jack, 5, North Vancouver, Canada
Podcasts are audio shows that people can listen to whenever they want to--unlike a radio program that you have to tune in to at the time it's broadcast. Podcasts are transferred over the internet. And anyone can make a simple podcast in a few steps:
1. Record your sound. Simple recordings can be made using a voice recording app on a smartphone or tablet. For better sound quality recordings, most podcasters use external microphones attached to a laptop or digital audio recorder. Professional podcasters usually record at a studio, where they have even better equipment and sound-proof rooms to record in.
2. Edit your sound. Sound editing is an art that takes years to master, but beginning podcasters can learn the basics using programs like GarageBand or Audacity. Play around with it; try taking out a word or layering two levels of sound--like the sound of music underneath your voice.
3. Post your podcast online. There are a number of sites that will host a podcast so that you can get it to other people. These companies and websites offer a wide range of services. Some sites are free and others require you to pay them for their service. Once you find the one that works best for you, you're ready to publish your podcast and send it out into the world.
