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.
Continue reading “Visual Ear Demonstrates How The Cochlea Works”
You might have heard of the cochlear implant. It’s an electronic device also referred to as a neuroprosthesis, serving as a bionic replacement for the human ear. These implants have brought an improved sense of hearing to hundreds of thousands around the world.
However, the cochlear implant isn’t the only game in town. The auditory brain stem implant is another device that promises to bring a sense of sound to those without it, albeit by a different route.
Continue reading “Auditory Brainstem Implants: The Other Bionic Hearing Device”
When auditory cells are modified to receive light, do you see sound, or hear light? To some trained gerbils at University Medical Center Göttingen, Germany under the care of [Tobias Moser], the question is moot. The gerbils were instructed to move to a different part of their cage when administrators played a sound, and when cochlear lights were activated on their modified cells, the gerbils obeyed their conditioning and went where they were supposed to go.
In the linked article, there is software which allows you to simulate what it is like to hear through a cochlear implant, or you can check out the video below the break which is not related to the article. Either way, improvements to the technology are welcome, and according to [Tobias]: “Optical stimulation may be the breakthrough to increase frequency resolution, and continue improving the cochlear implant”. The first cochlear implant was installed in 1964 so it has long history and a solid future.
This is not the only method for improving cochlear implants, and some don’t require any modified cells, but [Tobias] explained his reasoning. “I essentially took the harder route with optogenetics because it has a mechanism I understand,” and if that does not sound like so many hackers who reach for the tools they are familiar with, we don’t know what does. Revel in your Arduinos, 555 timers, transistors, or optogenetically modified cells, and know that your choice of tool is as powerful as the wielder.
Optogenetics could become a hot ticket at bio maker spaces. We have talked about optogenetics in lab rodents before, but it also finds purchase in zebrafish and roundworm.
Continue reading “Shining A Light On Hearing Loss”
If you wear cochlear implants, sound doesn’t enter through your ear, but rather from microphones above your ears. That means earbuds are useless and you have to resort to large and clumsy over the ear headphones. [Mjcraig23] wanted the convenience of earbuds and set out to do what we all do: hack it.
The result is handily portable as you can see in the video, below. The trick is that he used replacement battery covers and then grafted earbud holders (called EARBUDi) to them using one of our favorite fasteners, zip ties. Apparently, you can wire a cable directly into the device, but then you lose the ability to hear what’s going on around you, which would not be a good idea for catching some tunes while walking your dog or other common earbud use cases.
Continue reading “CIPODS: Earbuds For Cochlear Implants”
Hearing impairment, either partial or total, is a serious problem afflicting a large number of people. Almost 5% of the global population has some form of hearing disorder. For those affected by this disability from birth, it further impacts the development of language and speech abilities. In recent years, cochlear implants are increasingly being used to address this problem. These implants consist of two parts – the receiver and electrode array are implanted under the skin near the ear (with the electrode array terminating inside the Cochlea), while the microphone, electronics, transmitter and power source are attached on the outside. Often, the external unit has to be removed – for example, when the person needs to sleep. This is particularly so in the case of young children. The external unit is fairly large compared to their head and causes discomfort during sleep. And parents are worried that the expensive device could get damaged when the child is sleeping. This leads to the alarming situation where the child is asleep and has no audio sensory inputs being received from the surroundings. Not only can they not hear morning alarms, but also cannot react when there is an emergency situation such as a smoke alarm going off.
[Srdjan Pavlovic] came across this problem first hand when he visited his friend and learned about their six-year-old son with hearing loss since birth. The parents said their child will not be disturbed by loud noises at night since the external unit of his cochlear implant is removed each night. [Srdjan] then started work on building the Vibhear – an assistive hearing device to be used when the main hearing aid is removed or not working. It is a low-cost arm-band that provides a vibratory signal in response to high ambient noises.
The main components are a microphone, amplifier, microcontroller and vibration motor powered by a LiPo battery through a boost converter/charger. An RTC module allows setting up daily wake up alarms. It’s currently prototyped around the Arduino, but the next iteration will use a specialized DSP which can be programmed to perform signal processing operations on input sound. This will allow identification of specific sounds such as car horns, barking dogs, smoke alarms or emergency sirens.
[Srdjan] is in the process of choosing components for his next iteration, so if you have any recommendations to help him choose the microcontroller, power supply controller or other parts, do let him know via comments below.