By: Meghan Thoreau, OSU Extension Educator
This year’s STEM Club started by welcoming guest educators Dr. Betty Lise Anderson and Lecturer, Clayton Greenbaum, both from OSU’s Department of Electrical and Computer Engineering. Each led students to explore more concepts on vibration, sound waves, electromagnetism, magnet fields, current (I), and how to build an electromagnet to use in constructing a working speaker project to take home. It’s our hope that the students plug in their speakers and share what they learned in our club meeting with their families.
Dr. Anderson runs a popular ECE outreach program that helps K-12 students, and their teachers explore electrical and computer engineering concepts with a variety of hands-on electrical projects. This program is specifically designed to encourage students toward STEM fields and to specifically increase the number of women and minorities in engineering. In 2015, the program won Ohio State’s top university-wide Outreach Award.
Along with the team of Educators, several OSU college students’ volunteers, and Teays Valley High School volunteers came to mentor the elementary students and provide additional opportunities for students to engage and ask questions.
How does your ear process sound waves?
The bones in the middle ear amplify the sound vibrations and send them to the cochlea, which is filled with fluid. Once the vibrations cause the fluid inside the cochlea to ripple, a traveling wave forms along the basilar membrane. Hair cells, sensory cells, sitting on top of the basilar membrane—ride the wave. Hair cells near the wide end of the cochlea detect higher-pitched sounds, such as an infant crying. Those closer to the center detect lower-pitched sounds, such as a large dog barking.
As the hair cells move up and down, microscopic hair-like projections (known as stereocilia) perch on top of the hair cells bump against an overlying structure and bend. Bending causes pore-like channels, which are at the tips of the stereocilia, to open up. When that happens, chemicals rush into the cells, creating an electrical signal.
The auditory nerve carries this electrical signal to the brain, which turns it into a sound that we recognize and understand. (1)
What is an electromagnet?
An electromagnet is a coil of wire wrapped around a ferromagnetic material that becomes magnetized when electric current flows through it. Electromagnets are used in common electric devices. Here is a close-up of an electromagnet the students coiled up and attached to the base of their paper diaphragm.
Slow-motion video of speaker (note this one is driven by a source a little more substantial than a cell phone!) Credit: Clayton Greenbaum.
Why does a speaker need an electromagnet?
1 U.S. Department of Health and Human Services. (n.d.). How do we hear? National Institute of Deafness and Other Communication Disorders. https://www.nidcd.nih.gov/health/how-do-we-hear#:~:text=Sound%20waves%20enter%20the%20outer,malleus%2C%20incus%2C%20and%20stapes.