Using Tympan to build a voice changer

#1

Hi everyone,
I hope I’m posting this in the right place (apologies if not). I have a project that someone experienced in audio hardware/DSP could help with (I’d like to hire for it). I’m aiming to build two small, helmet-mounted systems:

1) Real-time formant-shifting voice changer (inside the helmet)

  • Reference: Chip’s Tympan demo - https://www.youtube.com/watch?v=xmHOsX0pL0w
  • will need help choosing mic/speaker/amp modules and potentially also implementing suppression/AEC
  • battery life: 2-3 hours with minimal added weight (basically the whole thing needs to be as small as possible).

2) Real-time “hearing” device for inside the helmet

  • The helmet makes it hard to hear people. I’ve tried exterior mics + headphones, which helped, but in noisy environments they pick up everything.
  • I’m looking for a solution that makes speech from someone in front of me clearly intelligible inside the helmet (directional mics maybe?).

I would love if these two systems can be a single unit, but if not possible that’s OK.

If this is in your wheelhouse, please reach out.

#2

Hi Vesnamd,

You’re project sounds so fun! Below are some thoughts that you might find helpful.

Cost:

What you’re looking to do seems very reasonable to achieve. But, the hardware cost (in addition to any additional cost of paying someone to do the development) might be a hurdle for you.

For your project, you will need one audio channel in/out for the voice changing and you will need at least two audio channels in/out for the hearing. So, that’s at least three channels of audio input and three channels of audio output.

The basic Tympan is a 2-channel device. So, to get 3 channels, you will need a Tympan + Tympan AIC Shield. The shield adds two in/out channels to the basic Tympan, thereby giving you 4-in and 4-out. Looking at the Tympan store, it looks like that will cost $329.99+$99.99.

Perhaps there are other products that’ll do it at a lower price, but by using a Tympan, you know that the Tympan library examples will make your software development easier.

Example Tympan Software:

For Tympan examples to help get you started, I recommend:

Microphones:

The Tympan can provide a 2V bias voltage, so you can use either small electret mics or you can use dynamic mics. To make things easy for yourself, the key is to ensure that you buy mics that use the typical 3.5mm TRS plug (instead of something larger like 1/4" or XLR plugs). With a 3.5mm plug, you can plug it straight into the Tympan without adapters. Here are some examples (I have not used any of these):

  • For Hearing: Low-cost stereo mic: Sony ECM-DS70P
  • For Hearing: Higher-cost, but directional, stereo pair of mics: MM-MCSM-5
  • For Voice: You might consider a headset that has both earphones and boom mic. Just be sure to get one with two 3.5mm TRS plugs, instead of the more-typical single 3.5mm TRRS plug. Here’s a low-cost example that clearly uses two plugs: NC-185

image

Loudspeaker:

The hardest part of your project, in my opinion, is choosing an amp+speaker so that people can hear your format-shifted voice. That’s tricky as you’ll need more output power to drive loudspeaker than the Tympan can provide via its headphone jack. The Tympan is made to drive headphones, not loudspeakers. So, you’ll need a product that can accept audio via a cable from the Tympan, amplify it, and pump it into the air via a loudspeaker.

Luckily, amplifying voice does not require especially large speakers or amplifiers (compared to amplifying music). So, searching around a bit, here are some example voice amplifiers that might be useful? (I’ve not used any of them)

Your project sounds fun!

Chip