- Perception &Wave Characteristics -

  • A Story: "The Day Gravity Failed"

  • Background: Things to think about as you Mess Around.

  • Focus: What should your focus be in this section?

  • Questions: Challenge questions which the Messing Around research is designed to answer.

  • Tools & Materials: List and description of tools and materials needed for Messing Around.

  • Activities: Hands-on activities which are components of the Messing Around research.


    While you are messing around with sound, you will build some important equipment for studying sound. At the same time, you will make important connections between what you hear and the sound waves that produce the mental sensation of sound. You will focus on three characteristics of auditory perception: pitch, loudness, and quality. You will try to connect these characteristics with five characteristics of waves: frequency, period, wavelength, amplitude, and waveform.

    On the physical level, sound as a mental experience is produced by an interacting array of discharging neurons in the brain. In contrast, a sound wave is a series of small density shifts (compressions and rarefactions) moving through a medium away from a vibrating source. The human ear, a marvelously versatile detector, converts sound waves into electrical signals which ultimately produce the sensation of sound. While they are not the same, the sensation of sound does convey information about the sound waves which produce it. That will be our focus while we mess around with sound.

    What are the connections between sound waves and the subjective impressions which they create in the mind of a listener? After some messing around with Pitching Practice, mess around with some real objects that ring, screech, hum, or toot. Found sounds are usually uncontrollable. Their pitch, loudness, and timbre are pretty much fixed. Science generally tries to bring some kind of order to what it investigates. In the next part of messing around with sound you will build electronic tools which will allow you to control sound. The sound generator you'll make allows you to plan the frequency and loudness of sounds it generates.


    Reading about focus in a section titled "Messing Around" may seem a little contradictory. It is not to most scientists. The difference between messing around and experimenting is not the difference between play and work or the difference between fun and drudgery. Most scientists enjoy their work. It can be drudgery (like any job), but usually it has an element of play and fun. For many scientists, the difference between messing around and experimenting is precisely a matter of focus. When scientists mess around, they usually have a broad focus. When they formally conduct an experiment, they usually have a narrow focus. So, what should your focus be in this section?

    If you want to use sound, it helps understand what sound is. To start, let's focus on the difference between sound as a mental experience and sound waves. This distinction may not seem important, but it is very useful to anyone who studies or uses sound.


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