Our world is filled with sounds of all kinds, from the birds chirping in your backyard to the indistinct chatter of conversations in a cafeteria to the scrolling of your mouse wheel as you browse this webpage.
Sound is important: we need it for so many reasons, such as communication, for when you want to tell your friend sitting next to you about how this webpage is pretty interesting, or for when your cellphone buzzes with a text message from your friend telling you about this webpage. We use sound for entertainment, such as when you want to browse YouTube for interesting videos explaining acoustic phenomena or for when you listen to music on your devices. Sound is especially important when it comes to communicating warnings and danger, such as when animals call to each to warn of nearby predators or the fire alarm goes off because somebody horribly burned some toast in your apartment complex.
So sound is a very important tool for life. Imagine a world without sound, as many people actually experience (or they experience it differently). Your perception of everyday things would be greatly changed.
But how do we explain sound? What exactly is happening when you hear your mom complaining that you're on the computer looking at this webpage for too long or you are at a concert and listening to your favourite musicians? Keep reading to find out. On these webpages you'll find out what sound is and how we hear sound, what 'waves' are, what do vibrations have to do with all this, what interference and resonance is, and how we use this knowledge in real-world applications. Using all this knowledge, you'll also learn how to build an active noise-cancelling circuit that you can connect to headphones!
These pages also contain documentation and supplies that can be used by teachers to present and teach this material to classes or to supplement the learning of their students.
Click one of the links below to get started!
Additionally, all the information in these webpages was presented to a class using this powerpoint presentation.
Here is the same presentation in a PDF form, with notes.