Mr. Hopper’s Eighth Grade Science students recently started their first unit: Waves. This week, they focused on learning about sound waves with the help of our Director of Music Rob DeNunzio. He shared some unique demonstrations and experiments to help students visualize the longitudinal waves of something very familiar: sound waves.

Using a spectrograph, he demonstrated the complexity of sound as it relates to frequency (pitch), amplitude (volume), melody and harmony. With the help of some brave student volunteers, they analyzed the sound of their own voices and demonstrated how sounds at certain frequencies cannot be heard. 

“We learned that what we experience as sound is really just differences in air pressure,” explained Mr. DeNunzio. “If those differences happen quickly and steadily enough, we experience them as musical pitch, which has frequency measured in Hertz. We used oscilloscopes and spectrograms to analyze the sound waves made by our voices, different musical instruments, and noises. We looked at what makes some musical sounds ‘warm’ or ‘cold,’ ‘round’ or ‘sharp,’ and tested theories of combining musical sounds that were either ‘pleasing’ or ‘dissonant.’” The students learned about the limitations humans have in the range of sound frequencies we respond to, experimenting with the extreme ranges of sound we can and cannot hear. 

Want to check it out for yourself? Try it here: https://spectrogram.sciencemusic.org/ A spectrogram allows you to see all the frequencies that combine to produce a sound. To try it out, make sure you allow the website to use your computer microphone. Then speak into the microphone and see what frequencies are present in your voice.

Spoiler alert: The older you get, the less you can perceive very high pitches!