Visual Ear Demonstrates How The Cochlea Works

April 2, 2023 by Lewin Day 13 Comments

The cochlea is key to human hearing, and it plays an important role in our understanding of complex frequency content. The Visual Ear project aims to illustrate the cochlear mechanism as an educational tool.

The cochlea itself is the part of the ear that converts the pressure waves of sound into electrical signals for the brain. Different auditory frequencies excite different parts of the cochlea. The cells in the different parts of the cochlea then send signals to the brain corresponding to the sound it has picked up.

The Visual Ear demonstrates similar behavior on a strip of addressable LEDs. Lower LEDs coded in the red part of the color spectrum respond to low frequency audio. Higher LEDs step through yellow, green, and up to blue, and respond to the higher frequencies in turn. This is achieved at a high response rate with the use of a Teensy 4.0 running a Fast Fourier Transform on incoming audio, and then outputting signals to run a string of WS2812B LEDs. The result is a visual band display of 104 bands spanning 43 Hz up to 16,744 Hz, which covers most but not all of the human range of hearing.

It’s an impressive display, and one that makes a great music visualizer, too. When teaching the physics of human hearing and the cochlea, we can imagine such a tool would be quite useful.

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Hackaday Links: June 5, 2022

June 5, 2022 by Dan Maloney 16 Comments

The big news this week comes from the world of medicine, where a woman has received a 3D-printed ear transplant. The 20-year-old woman suffered from microtia, a rare congenital deformity that left her without a pinna, the external structure of the ear. Using scans of the normal ear, doctors were able to make a 3D model of what the missing pinna should look like. Raw material for the print was taken from the vestigial ear of the patient in the form of cartilage cells, or chondrocytes. The ear was printed using a bioprinter, which is a bit like an inkjet printer. The newly printed ear was placed into a protective structure and transplanted. The operation was done in March, and the results are pretty dramatic. With a little squinting, it does look a bit like there are some printing artifacts in the ear, but we’d imagine that’s more from the protective cage that was over the ear as it healed.

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Custom Headphones Solve Wire Tangles

May 1, 2010 by Jakob Griffith 27 Comments

One complaint we hear about often is ear-bud’s cables getting tangled within backpacks. [Andrew] was having this “spaghetti” wire problem, and also wanted to listen to his music with ear protection on – where ear-buds are usually uncomfortable. The latter problem is fixed by placing speakers inside of folding ear protectors, and the cable is managed with a 3.5mm disconnect.

For those who can’t make disconnect-able headphones but still suffer from tangled headphone wire, we recommend proper wrapping technique for your wire, and a small carrying pouch. With the combination of the two, we’ve never had a tangled cable.