Hacking Hearing with a Bone Conduction Bluetooth Speaker

When a hacker finds himself with a metal disc and magnet surgically implanted in his skull, chances are pretty good that something interesting will come from it. [Eric Cherry]’s implant, designed to anchor a bone-conduction hear aid, turned out to be a great place to mount a low-cost Bluetooth speaker for his phone – at least when he’s not storing paperclips behind his ear.

With single-sided deafness, [Eric]’s implant allows him to attach his bone-anchored hearing aid (BAHA), which actually uses the skull itself as a resonator to bypass the outer ear canal and the bones of the middle ear and send vibrations directly to the cochlea. As you can imagine, a BAHA device is a pretty pricey bit of gear, and being held on by just a magnet can be tense in some situations. [Eric] decided to hack a tiny Bluetooth speaker to attach to his implant and see if it would work with his phone. A quick teardown and replacement of the stock speaker with a bone-conduction transducer from Adafruit took care of the electronics, which were installed in a 3D printed enclosure compatible with the implant. After pairing with his phone he found that sound quality was more than good enough to enjoy music without risking his implant. And all for only $22 out-of-pocket. While only a Bluetooth speaker in its current form, we can see how the microphone in the speakerphone might be used to build a complete hearing aid on the cheap.

We think this is a great hack that really opens up some possibilities for the hearing impaired. Of course it’s not suitable for all types of hearing loss; for more traditional hearing aid users, this Bluetooth-enabled adapter might be a better choice for listening to music.

20 thoughts on “Hacking Hearing with a Bone Conduction Bluetooth Speaker

    1. Shortly after I got my hearing implant I bumped the processor against a doorjamb got ripped off my head and watched it tumble down a double flight of concrete stairs. Watching it shatter more and more with each step it landed on. Totally ruined it beyond repair. I sat there with it in my hand more bummed out than I ever had been. It’s so prohibitively expensive that it’s like buying a new car, pushing it off a cliff and watching it tumble down. Lucky for me the company who made it gave me another one free of charge (which might be some insight just how much profit margin these things have).

      They are so expensive and honestly so underwhelming in performance that I’ve taken on the personal project of trying to make my own BAHA hearing aid. With my not being an electrical engineer I know I won’t be able to get it as small as the commercial offerings. But my idea is to make it work like an MP3 player, magnet the transducer to my head, run a wire down to a mic/amp that I’d wear on my hip or in a shirt pocket.

      I’ve cobbled together a prototype using some modules I bought from adafruit/sparkfun and as an idea it seems to be working out. Tho with some more learning I plan to do another from scratch to get the size/cost down. Again, the goal is to offer an inexpensive alternative to the BAHA for use in environments where it can be lost/broken or as a back-up hearing aid. Hell, I want one just to fall asleep watching TV with it.

      1. For what it’s worth (watching a single father in our church struggle to come up with funds for a BAHA for his daughter), I truly wish you all the best.

        This is an industry in desperate need of an open source / open hardware solution.

  1. With modern DSP capabilities, I really struggle to fathom why any device for hearing impaired costs more than set of good studio monitor headphones.

    I’ll admit, since I (fortunately) don’t require one, I really don’t understand what kind of technology is required. But I assume it is a microphone, pre-amp, parametric EQ, limiter/compressor, amp, speaker (and a battery to keep it running).

    I hope this guy takes his low cost device further and engineers an open source / open hardware module for those without insurance.

    1. It’s what the market will bear. A lot of hearing loss appliances are covered by insurance or some other third-party compensation and the providers know it and are out to squeeze the system for all they can. It’s a racket, and you are right: it’s crying for an open source solution.

      1. @timgray1
        To elaborate, medical devices and procedures tend to be inelastic goods: if you need one, you need one. You’ll get it whether it’s $3,000 or $30,000 unless you’re priced totally out of the market. Yet if they were suddenly $3 you wouldn’t get a truckload.

        Compare this to things like jewelry and fancy-pants restaurants, where demand at a given price is highly dependent on, eg, how the economy is doing.

        The situation certainly isn’t helped by the financial burden of certification (and god help you if you’re injured by a device that isn’t certified) but the biggest burden for end users is the result of economics.

        Well, that and companies being obligated to maximize value to stakeholders. But that’s not something you can address without nationalizing the companies either in fact or in practice (ie regulated to the point where they might as well not be capitalistic enterprises). This is why most countries attack the other end of the problem using a single payer system, so the companies get to choose between taking what the government will pay and not selling anything at all.

        1. > This is why most countries attack the other end of the problem using a single payer system, so the companies get to choose between taking what the government will pay and not selling anything at all.

          That’s exactly the same as regulating the product to the point that it’s no longer a capitalistic enterprise.

          If there’s not profit to be made, the product won’t be developed, let alone manufactured.

          The regulation/certification is a huge part of the problem. In this case, the official devices are extremely expensive because they have to go through so much certification.

          The consumer devices that have been pointed out here cost < $200 and don't require any surgery or embedded metal plate. Are they as good? That depends how you evaluate them. In some cases they are better, in other ways they are not quite as good. But because they are not certified, there is no way to get insurance to pay for them (although, I wouldn't be surprised if getting some of these consumer solutions didn't end up being cheaper than paying the part that insurance doesn't cover for the 'approved' solutions.

  2. If a way could be figured out to externally engage the telecoil that is in most models of hearing aids without having to use a neck worn transceiver, this would be a moot issue. I am a wearer of “Behind The Ear” (BTE) hearing aids and have a transceiver which is neck worn via its inductive loop. This transceiver connects to my phone via bluetooth and passes audio to my HAs via the inductive loop to the telecoil inside my HAs. There is also a 3.5mm jack on the bottom of it for non-bluetooth audio sources to connect via a standard stereo audio cable. When I’m wearing it, it works fine, but I do get some second looks at times because the transceiver lays on your chest in the same area that a neck worn police badge lays. But a bone conduction rig, or even the cochlear implants would be much better at offering the “normal” visual aesthetic.

    1. You can buy (commercially) inductive-loop headphones – essentially headphones with the speaker cone removed. They look like headphones, but no sound comes out, and they drive the hearing aid’s telecoil input when placed in the vicinity of the aid. As you probably know, however, there’s a lot of interference in the real world which means the telecoil is a bit of a compromise (try using telecoils on an electric train for example… hopeless). I use the direct audio input leads with a Samsung, and more latterly a Sony, bluetooth adapter which already has the 3.5mm jack. At a casual glance, looks no different from in-ear buds.

  3. Good to see this, I’ve been working on something similar, also with the adafruit bone conduction transducer, in an attempt to help dear ol’ deaf dad hear a bit better. This will motivate me to get the project moving along, thanks!

    1. I bought something similar made by Aftershokz. I bought them as an experiment to see if I would actually benefit from the surgery or not. Just listening to music/podcasts, using a splitter and using a headphone in one ear/Aftershokz on and adjusting the balance till I felt I was hearing the same volume in the left/right channels equally. In reality the Aftershokz I bought produce better/louder sound than the BAHA I got from Cochlear. My hack still trumps the Aftershokz as the metal disc isn’t just to hold the processor on, it helps resonate sound a lot better than the bone in my skull does alone.

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