The Sound of Science 2: Wave Motions on the Tectorial Membrane

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Submitted by Jonathon Sellon in the Research Laboratory for Electronics at MIT

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This image is a single frame from a stroboscopic video depicting wave motions on the tectorial membrane––a hydrogel that overlies hair cells in the inner ear. As sound waves enter the ear they are transmitted from the middle ear bones to the fluid filled inner ear, also known as the cochlea. Within the cochlea there are tiny receptors called hair cells that transform this mechanical energy into electrical signals that the brain can interpret. The last mechanical step in this cascade involves the propagation of waves on the tectorial membrane to stimulate these hair cells. Our goal was to understand how the underlying molecular properties of the tectorial membrane contribute to its wave properties and how these in turn contribute to our ability to parse out sounds of different frequencies.