Introduction
This experiment is a little different than my other experiments that had a little more to do with a particular type of wave. This experiment is more focused on vibrations in general. This is an experiment using a plastic tube or container, a balloon, a small mirror, a laser pointer, and some sort of mount for the container. There are different ways to execute this experiment, but in my case, I used a container that was open on one end and closed at the other end. A speaker was placed inside the container with a balloon stretched over the open end. A mirror was taped onto the outside of the balloon. A laser was pointed at the mirror at a bit of an angle. The laser light that reflected should be pointed at a wall. When sound is played through the speaker, the vibration of the balloon causes the laser to “draw” on the wall; thus allowing for sound to be visualized. When you play music through the speaker you’ll most likely get what looks like a big scribble on the wall, but when you play pure tones or frequencies you can see distinct clean shapes. For example, different variations generate ovals. The reason for this is easy to see if you picture the movement of the balloon. Picture the membrane moving in a back and forth motion, it would create a line with the laser. Now add a little bit of motion in the opposite direction to create a more circular motion. This is what causes ovals to appear. The width and length of the oval depends on how much the balloon vibrates in each direction.
Methodology
The materials for this project include: a plastic container, a smaller Bluetooth speaker, a balloon, hot glue, a laser pointer, wood for the mount, a small mirror, and an online tone generator. For the mount, I used large wooden popsicle sticks and paint mixing sticks. I glued the mixing sticks together for the base then glued together smaller pieces of the popsicle sticks that I had cut up as a mount for the plastic container. I then glued the container to the mount. I set a Bluetooth speaker inside the container and covered the open end with the balloon, and taped the mirror onto the outside of the balloon. I then played music or frequencies through the speaker to vibrate the balloon. I pointed the laser towards the mirror and made sure the reflection pointed towards the wall. I captured still photos of the designs created.
Results
I tested a range of frequencies from 730Hz to 37Hz I started by simply sliding through these frequencies and observing the shapes change.
This is a video of the laser with a range of frequencies from 200 Hz to 730 Hz
I then repeated this but stopped at the frequencies that I believed created the most interesting or most defined shapes. I isolated 5 frequencies from 362 Hz to 67Hz. These are the pictures of the 5 shapes with their frequencies.
After testing the different frequencies, I decided to have a little fun and tested the laser out with songs from different genres of music. The songs I used were Ya Tú Sabes- CNCO, Cometa- CNCO, Mozart symphony No. 40, Happy Does- Kenny Chesney, Ocean- Karol G, and Bad Guy- Billie Eilish.
Mozart symphony No. 40
Bad Guy- Billie Eilish
Cometa- CNCO
Happy Does- Kenny Chesney
Ocean- Karol G
Ya Tú Sabes- CNCO
Discussion
This experiment was more complicated than I had anticipated. The first problem arose in finding a laser pointer. No local store carried them and online stores would not deliver until the end of May. I ended up borrowing one from my mom’s work friend. The mirror also proved difficult to find because of the lack of open craft stores and delays in shipping non-essential items. I had to break open a make-up compact and take the mirror out of that. Balloons were also hard to come by. Grocery stores did not have them and although I found them at Walmart, when I drove there to pick them up, the employees were too busy and could not bring them to me. I finally found one pack at Walgreens. I cut the closed end of the first container. I cut the small end of the balloon off and stretched it across one of the open sides of the container. I taped the small mirror to the outside of the balloon and shined a laser too test it out. I tried to talk into and play tones through the open end of the container, but the open end of the container turned out to be too big and did not generate a strong enough vibration to shake the balloon, so I had to try something else. I then got a second container, I connected my computer to the speaker, I placed a Bluetooth speaker in the container, I placed the balloon on the open end of the container and taped the mirror to the balloon. I then hot glued the container to the wooden mount and this generated enough vibrations to create visual images on the wall when I shined a laser into the mirror while playing tones.