SOUND - Extensions Story

Hands-On-Physics: SOUND



Waves in a Stream

It's the first day of a three day weekend. I decided to go for a walk. The ground is covered with snow, but it's not very deep. While walking, I make this amazingly loud crunching sound as I break through the crust on the snow. When I stop, the world is completely silent like that space I imagine between the stars.

The sun is moving between cloud and sky as I move between forest and meadow. The result is a shifting shadow play of change and contrasts. Light and dark in motion, a fitting backdrop for my thoughts. Gwen's mood has shifted. She has been reading about medical research on her disease. Doctors are beginning to understand its physical and biochemical cause and are hopeful that a cure can be found in the near future. As Gwen's vision loss will be slow, she is hopeful that a cure will be found before too much irreparable damage is done. I'm pleased to see Gwen talking more, and she actually smiled yesterday. I try to be positive and upbeat, but inside, I'm uncertain and concerned. Is this just false optimism masking her hurt and delaying acceptance of her condition? How is Gwen going to react in the future if a cure isn't found? It's hard to know what is best. Yesterday, we finished the core project of our sound unit, I feel more confused than ever. I was sure that loudness was the perfect range finder. In fact, there are several problems with this idea. As you move away from a sound source, it quickly gets difficult to hear the change in loudness as you move further away. Under the right conditions, even more startling things can happen.

A sound can actually get louder as you move away from the source, or quieter as you move towards it. In addition, sound navigators face a problem which has always plagued astronomers. It would seem like a simple matter to judge the distance of a star by its brightness. Bright stars are close. Faint stars are distant. However, it's not so simple. When you see a bright star, is it a distant supergiant or a nearby dwarf? In the same way, how do you interpret a soft sound when you don't have any information about the source except the sound?

Is it quiet and nearby or loud and distant? I'm baffled. How do visually-impaired people use sound to get around? Gradually, the sound of my own breathing came to my attention. I was huffing and puffing and starting to sweat.

Lost in my thoughts, I had climbed the saddle at the head of our valley. Before me was the next valley. I turned around. I could see the radio telescope, my home, Gwen's home, and the other buildings in the distance. I decided to head back. My thoughts changed direction along with me. I started thinking about the coming week. On Tuesday, we will start small group research projects in the area of sound. We have more freedom to follow our own interests. I am really looking forward to this. While I feel a little frustrated in my search for knowledge about Gwen's future, I really like the topic of sound. I especially like the idea of sound waves. There are waves in the little stream beside the trail, in the clouds above, and in the trees as the wind starts to blow. I keep finding waves all around me. I've seen these things before, but I didn't recognize the common pattern, a pattern that extends to also take in sound and even light. What a wonderful, surprising world!
To be continued...

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