McIntosh Teaches Kids to See Sound
Author: Chuck Hinton of McIntosh Tech Support
As soon as the children enter the room, they are enthusiastically asked; “How many of you have seen sound today?” Quick to respond without thinking, most of the hands in the room shoot up, then the raised hands slowly sink back down as they realize what they have responded toâ€¦ quizzical looks abound amidst protestations and confusionâ€¦ “You cant see sound” some respondâ€¦ before they have time to think it any further through, they are asked to draw a picture of sound.
Roberson Super Science Day, an annual event at the local Binghamton, NY art and science museum, brings local businesses into the museum to set up displays on science and how it relates to the companies’ business. This is for grade school children to learn how real world applications of science apply to careers they might want to one day explore.
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This was McIntosh’s third year participating in the program. The theme was, “How do you see sound?” Children were taught how sound can be measured and displayed, how sound travels and how sound is created.
As soon as the children enter the room, they are enthusiastically asked; “How many of you have seen sound today?” Quick to respond without thinking, most of the hands in the room shoot up, then the raised hands slowly sink back down as they realize what they have responded toâ€¦ quizzical looks abound amidst protestations and confusionâ€¦ “You cant see sound” some respondâ€¦ before they have time to think it any further through, they are asked to draw a picture of sound. A few jump right to work; others are at a loss for what to do. “There are no wrong answers” the children are re-assured, and the drawings come forth. A speaker, boom box or openmouthed person with curved lines emanating from them is a common depiction, as well as things that look like the ripples made by a stone thrown in a pond, squiggles similar to the trace a sign wave makes on an oscilloscope, musical notes, musical instruments and more.
The drawings are then shown to the class, the squiggles are a sign wave, the pond ripples are an omnodiectional radiation pattern, the curving lines in front of the mouth are a unidirectional radiation pattern and the musical notes are instructions on how to make sounds. In nearly every class there is a kid who simply can not bring them selves to put something on the paper, the blank sheet is held up in front of the class, “Is this correct?”, the class is asked, “is this a drawing of sound?”. Most of the group shakes their heads or quietly says no, the kid who left the paper blank looks crestfallen… “Of course this is correct! This is a perfect drawing of sound! â€˜cause you cant see sound!!! DUHH!!!” The truth starts to sink in, there really is no wrong answer; you can see, measure and draw sound in as many ways as you can imagine sound to look like.
A McIntosh integrated amplifier, with a server and signal generator connected sits atop a table, one bookshelf speaker and grill-less sub-woofer are on the outputs. The integrated also has a tape out connected to a laptop, its video sent to a projector. A spectrum analyzer is brought up on the computer, vertical bars represent the amount of energy in the signal at each frequency, one tall bar rolls across the screen as the frequency is increased on the tone generator. A microphone is then brought around the room, children see the pitch of their voice on the graph, far to the right when they do that little squeak thing kids do, off to the left when they say ” Luke, I’m your Father” in James Earl Jones imitation mode.
The Display is then switched to an Oscilloscope; the class observes the smooth, sweeping wave of the tone generator, noting the waves getting closer together and farther apart as the pitch goes up and down. A complex signal, recorded music, is fed to the display and the children marvel at the chaos of the complex waveform. The microphone comes back out; children excitedly jostle and reach for their chance to â€˜see’ their own sound on the displayâ€¦ Once again they observe the waves getting closer together on high pitched sounds and farther apart on low pitches and how louder sounds make taller waves and quieter sounds making shorter waves, repeating back the terms of frequency and amplitude as they learn them.
“So, how does sound travel?” A plethora of theories come out, and the kids are led through the process of revealing that sound travels by vibrating air molecules. To demonstrate how each air molecule passes its energy on to the next, a jump rope is laid out on the floor. A flick of one end causes a little hump of rope to lift off the floor and travel along the length of rope, each little bit of rope passes its energy on to the next and the little hump travels across room, just as sound waves do. To demonstrate the point further, a half dozen kids are brought to front of the room, the first told they are a mouth, the next four are air molecules and the last is the ear. The â€˜mouth’ is told to make a sound, and then given a gentle shove toward the rest. Each child bumps into the next; the energy of the shove makes its way down the line, with the â€˜ear’ getting knocked into by the last air molecule. Despite hysterical giggles and excitement, the lesson is one unlikely to be forgotten.
The finale is a demonstration of how sound is created, the children gather around the subwoofer while the tone generator is swept through low frequencies, with their hands on the cone, the kids squeal and giggle as their hands are furiously vibrated by the cone. The generator is run down to just a few Hertz and children note the slow vibration of the cone, observing its increase in speed as frequency increases.
Well over 1,000 kids went through the demonstration over the three years McIntosh participated in this event, most walking away with a better understanding of sound, many garnering an increased interest in science and few cursed with the audiophile obsession so many of us suffer from.