Question for Tympan folks (use case idea)

As posted on this forum I’m working on a bone-conduction hearing system and I’ve got it up and running. I’ve had an idea for a specialized use-case and I wanted to ask for some feedback:

All sorts of professional service providers have to deal with clients/patients who do not have hearing aids or are non-compliant in the use of them. People like social-workers, medical personnel, paramedics, nursing home workers, etc. Communication is often critical when these folks encounter people.

One of the nifty things about bone-conduction is that nothing goes into the ear canal. Secondly, it can overcome a certain degree of conductive hearing loss (blocked ear canal, problems with the ear-drum or those tiny little bones, etc.). Thirdly, after use on a patient/client it’s surfaces can be completely disinfected with an alcohol wipe (no little holes to worry about).

A version of this device with an over-the-head headset could be useful. You plop the headset on the client-patient, assist them in adjusting the volume and you instantly have improved hearing (dependent,of course, on the root cause of their hearing loss). Pre-programming with a basic age-related hearing loss sketch (high-frequency enhancement) would do the trick in a lot of cases.

My next prototype will have mics on the top of the box for those who want to hang it around their neck. I’m including a selection switch that lets you toggle between that and a standard jack. You could plug in a handheld mic and use that to further eliminate background noise, etc. That would also get the mic far enough away from the wearer to pretty much eliminate feedback, and you could use the full power of the device. It will be feeding 3 watts per ear into 3 watt transducers, and with that you could probably communicate with a chunk of granite.

Anyone know of anything likes this out there? Thoughts??? Is this silly???

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Cool idea.

Regarding the small question of switching back and forth between mics and an input jack, most audio codec chips have multiple analog inputs per channel. It’ll still only digitize a stereo pair, but you can switch between or arbitrarily mix the multiple analog inputs.

This is what the Tympan does, for example. Its audio codec chip has three pairs of inputs. The Tympan has two mics on its PCB. They are connected to one set of inputs. The Tympan also has the pink jack for external audio inputs. That uses another set of inputs on the audio codec chip. And, finally, there is another set of inputs in the pin headers on the sides of the Tympan. These use the third set of inputs. When using the Tympan, you can easily switch between these inputs (or mix them) on the fly.

As for other products in this space, there are the so-called “FM systems” that are often used for the hearing impaired, most often in schools and in performance halls or lecture halls. Usually they’re air-conducted headsets (ie, headphones) but perhaps they have bond conduction headsets, too. If you’re interested, you’d have to Google around a bit.



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This is a great idea.
My main work is doing consulting for companies and artists/designers. Before the pandemic, I spent some time with a company called Audiome ( based in France. Their idea was to have a bone conduction + speaker + mic all in a headset. The headset would be ‘owned’ by a care-giving facility and used when a caregiver needs to communicate with a resident. I think that is essentially what their model was.
The biggest problem with the system was the original design to have the mic on board with the speaker + bone conduction. The headset design in general just doens’t have enough inertia, and when the bone conduction runs, the entire system vibrates. It became too difficult to damp and isolate the mic from the rest. I would say that it is an extreemly difficult challenge.
If, however, you can design with the mic on the lapel, for example, I don’t see why this would not work great.

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Thanks guys!

Chip: Thanks for the info! For the moment I’m using a physical switch for choosing the mic source because I want to keep this thing as simple to operate as possible for non-techy old people.

Way back in another lifetime I was the theater manager for the American Conservatory Theater in SF. We had a system made by Sennheiser that we lent out for the hearing impaired. It was very popular for matinees! We had on stage mics feeding into a mixer and then the transmitter which the headsets picked-up nicely. This was (still is) legit theater, in that no amplification is normally used. Actors really had to learn to project and diction was critical.

Biomurph: As you can see from the attached pic the current iteration has the mics mounted to the top of the box, lanyard hung around the neck. These mics swivel, so you can point them out for greater spacial awareness or bring them in for a point source (like someone sitting across the table talking). As you’ve pointed out, dealing with feedback when the mics are on the headset is a nightmare. I even printed some fancy mic holders from very soft TPU with springy things and baffles. An improvement, but nowhere near enough. Now that I’ve got this new arrangement I’m going to experiment with lengthening the barrel to see if I can get a shotgun mic effect and be more critically selective.

Because I have an innate tendency to complicate things I’m also pondering a display on the front and a single programming button. The idea is to start with the users audiogram and then have a handful of modes (with compression, added high frequency boost, noise reduction, etc.). I’ve never in my life used a display, so it should be fun to figure out.

Thanks so much for being responsive and providing feedback!


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Hi Robert,

The idea with the multiple inputs on the audio codec chip is NOT that you expect that the user issue a software command.

Instead, the idea is that your switch is read by the processor and that the processor issues the software command to have the chip switch it’s inputs. To the user, it looks the same as any basic switch. But you, the builder, get the freedom of keeping the audio signals separate.

In fact, the Tympan can already detect when a plug has been inserted into the pink jack. When this feature is activated, the processor can respond by automatically commanding the chip to switch it’s input to the pink jack. Handy!

But none of this is relevant if your own setup is working for you. Absolutely, stick with what works!

Good luck with your project. I look forward to hearing about your progress!


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Great looking case.
The Tympan hardware always comes with two MEMs microphones already built in, so when you get your Rev E, you will have the option to use those instead of the lapel mics you are already using.

Fun stuff!

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