JimGo
Posts: 2
Joined: Sun Aug 27, 2017 2:21 am

Hearing impaired: need to implement Bluetooth audio loopback

Sun Aug 27, 2017 2:51 am

I am hearing impaired, which means I need to wear hearing aids to hear well. Unfortunately, hearing aids being electronic, they don't typically work well around water, unless you're willing to spend many thousands of dollars for a pair. This is a bit of a problem, because I also have kids, and they love to be in and around the water. So, I have decided to try to repurpose an existing waterproof Bluetooth headset for use as a hearing aids. I want to take the sound coming in from the headset's microphone, amplify it (ideally, although I'd be OK with skipping this for now), and then send it back to the headset's speakers. I have a Raspberry Pi Zero W, to which I will add a 5v battery (a USB charger battery) and make a waterproof case (or carry it in a ziplock back inside another ziplock bag), which I want to use to do the processing. Obviously, I'll need the Pi to be set up in headless mode so it can be portable.

My biggest problem right now is that I don't speak Bluetooth or Linux/Raspberry Pi well enough to do effective online searching to help me research how to actually implement what I want to do. I keep finding instructions for using Bluetooth via existing, higher-level apps like Kodi or some of the music players, but nothing that will help me figure out how to read from and (simultaneously) write to the same Bluetooth device. I used to write n-tier, Visual Basic-based applications a long time ago, so the idea of writing code to do what I want doesn't scare me. I'm not that familiar with some of the more modern languages like Python or Java, but I'm not averse to learning. Can anyone point me in the right direction?

All help is appreciated!

MikeDK
Posts: 79
Joined: Thu Mar 19, 2015 12:01 pm

Re: Bluetooth audio loopback

Sun Aug 27, 2017 7:48 pm

I guess the most effective way to do this would be via Jack, as it is designed for audio production and thus low latency. See http://libremusicproduction.com/article ... arted-jack
Using JACK will allow you to achieve low latencies with both audio and MIDI. This means that if you are recording an instrument into your computer, you can monitor the audio back through your speakers, or headphones, without any perceivable delay.
I have read that the new Raspbian uses ALSA for Bluetooth Audio instead of Pulseaudio, so I think it would be kind of easier now.

You have to get the Headset running as ALSA device and use it in the jackd Audio Server.

There you can "plug" inputs/outputs of any audio device as you like ... I would test this on a Desktop first, then save/copy configuration to RPi Zero and load it via command line....

I know from personal experience (my wife is hearing impaired and I had to get bluetooth headsets to work in kodi) that bluetooth audio under linux can be a pain in the ass, but you may be lucky and have a device which works well ;)

JimGo
Posts: 2
Joined: Sun Aug 27, 2017 2:21 am

Re: Bluetooth audio loopback

Mon Aug 28, 2017 12:51 am

Thank you Mike!

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