We are accustomed to medical devices being expensive, but sometimes the costs seem to far exceed reasonable expectations. At its most simplistic, a hearing aid should just be a battery, microphone, amplifier, and speaker, all wrapped in an enclosure, right? These kinds of parts can be had for a few dimes, so why do modern hearing aids cost thousands of dollars, and why can’t they seem to go down in price?
If you’ve ever seen an experienced radio operator pull a signal out of the noise, or talked to someone in a crowded noisy restaurant, you know the human brain is excellent at focusing on a particular sound. This is sometimes called the cocktail party effect and if you wear a hearing aid, this doesn’t work as well because the device amplifies everything the same. A German company, Fraunhofer, aims to change that. They’ve demonstrated a hearing aid that uses EEG sensors to determine what you are trying to hear. Then it uses that information to configure beamforming microphone arrays to focus in on the sound you want to hear.
In addition to electronically focusing sound, the device stimulates your brain using transcranial electrostimulation. A low-level electrical signal tied to the audio input directly stimulates the auditory cortex of your brain and reportedly improves intelligibility.
Imagine being asked to provide sound reinforcement for a meeting that occurs in a large room, where anyone can be the speaker, and in a situation where microphones would hinder the flow of the meeting. Throw in a couple of attendees who have hearing disabilities, and you’ve got quite a challenge to make sure everyone gets heard.
Such a situation faced [David Schneider] at his Quaker meetinghouse, which he ended up solving with this home-brew audio induction loop system. The worship style of conservative sects of the Religious Society of Friends, as the Quakers are formally known, is “silent worship”, where congregants sit together in silence until someone feels moved to share something. Anyone can speak at any time from anywhere in the room, leading to the audio problem.
Rooms mics and a low power FM transmitter didn’t work because those using radio as aids to hearing the service felt awkward, so [David] decided to take advantage of a feature in the hearing aids worn by some members: telecoils. These are inductive receivers built into some hearing aids to send sound directly to them using magnetic fields generated by a loop in the listening area. [David]’s loop ended up being 240 meters of 20-gauge copper wire in the attic above the meeting room. The impedance ended up close to 8 ohms, perfect for feeding directly from the speaker terminals of an old stereo amplifier. Pumping 160 Watts into the coil allows the hearing-aid wearers below hear the service now.
There’s still work to be done on the input side to improve audio quality, but [David]’s solution is elegant in that it helps those who need it most using technology they already have. And perhaps those who need but don’t yet have hearing aids can roll their own.
If you’re the kind of person who’s serious about using open source software and hardware, relying on a medical device like a pacemaker or an insulin pump can be a particular insult. You wouldn’t trust the technology with your email, and yet you’re forced to put your life into the hands of a device you can’t examine yourself. Unfortunately we don’t (yet) have any news to report on open source pacemakers, but at least now there’s an open software and hardware hearing aid for those who need it.
The Tympan project aims to develop a fully open source hearing aid that you can not only build yourself, but expand and modify to fit your exact specifications. Ever wanted to write code for your hearing aid with the Arduino IDE? No problem. You want Bluetooth, I2C, and SPI? You got it. In truth we’re not sure what this kind of technology makes possible just yet, but the point is that now those who want to hack their hearing aids have a choice in the matter. We have no doubt the community will come up with incredible applications that we can’t even begin to imagine.
But these open hearing aids aren’t just hackable, they’re affordable. Traditional hearing aids can cost thousands of dollars, but you can buy the Tympan right now for $250. You don’t even need to check with your health insurance first. Such a huge reduction in price means there’s a market for these outside the hardware hacking crowd, and yet another example of how open source can put cutting edge technology into the hands of those who would otherwise have to go without.
The latest version of the Tympan hardware, revision D, is powered by the Teensy 3.6 and features a Sierra Wireless BC127 Bluetooth radio, dual MEMS microphones, and even a microSD slot for recording audio or logging data. It might be a bit bigger than the traditional hearing aids you’re used to seeing, but with an external microphone and headphone setup, the wearer could simply keep it in their pocket.
We’ve seen DIY hearing aids before, but unless you’re willing to carry a breadboard around with you, they’ve generally been limited to proof of concept sort of builds. We’re glad to see a mature project like Tympan join the growing movement for open source medical hardware; it’s a another big step forward towards democratizing these critical pieces of technology.
We are swimming in radio transmissions from all around, and if you live above the ground floor, they are coming at you from below as well. Humans do not have a sensory organ for recognizing radio signals, but we have lots of hardware which can make sense of it. The chances are good that you are looking at one such device right now. [Frank Swain] has leaped from merely accepting the omnipresent signals from WiFi routers and portable devices to listening in on them. The audio signals are mere soundwaves, so he is not listening to every tweet and email password, merely a representation of the data’s presence. There is a sample below the break, and it sounds like a Geiger counter playing PIN•BOT.
We experience only the most minuscule sliver of information coming at us at any given moment. Machines to hack that gap are not had to find on these pages so [Frank] is in good company. Magnetosensory is a popular choice for people with a poor sense of direction. Echolocation is perfect for fans of Daredevil. Delivering new sensations could be easier than ever with high-resolution tactile displays. Detect some rather intimate data with ‘SHE BON.’
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.
Hearing aids are probably more high-tech than you think. They are tiny. They have to go through a lot of trouble to prevent feedback. They need a long battery life. The good ones match their amplification to the inverse of your hearing loss (amplifying only the bands where you don’t hear as well).
[NotionSunday] put together a hearing amplifier project that probably doesn’t hit many of those design criteria. However, thanks to a 3D printed case, it looks pretty good. The device uses a dual opamp to boost the output from two microphones and feeds it to a conventional headphone.