Misophonia: white noise with remote microphone for school use

A portable white noise generator can mask misophonia trigger sounds. Unfortunately, in the classroom the white noise also masks the teacher's voice. What if we could give the teacher a portable microphone and mix their voice into the white noise?

I experimented a lot with smartphone apps, mixers, directional microphones, etc. The following is my quick-and-dirty solution. Note that this design could potentially damage your electronics, your hearing, or both. That said, my son uses this setup at school most days.

Parts:
Sony ECMAW4 Wireless Microphone
Monoprice 107128 3.5mm Mono Plug to 3.5mm Stereo Jack Adaptor
Monoprice 6-Inch 3.5mm Stereo Jack Splitter for Mobile
    Not a headphone/microphone splitter. Shop carefully, this is an uncommon item.)
Sound Oasis S-001 Portable White Noise Machine
Sennheiser PX 100 Lightweight Collapsible Headphones
    Discontinued. Try eBay or see below.

(Teacher microphone not shown.)

Connect as shown in the photo above. Before putting on headphones, turn on both microphones, wait for the flashing blue light to turn solid, then turn on the white noise. You'll hear both noise and sound from the remote mic. You will need to carefully adjust the noise volume in order to hear both.

Warning: Ensure that both the microphone and white noise generator turned on while adjusting volumes. Take off the headphones before turning off the mic or the noise. Turning off the microphone first will double the white noise volume and could damage your ears.

This setup is finicky because it doesn't contain an audio mixer. We're just gluing together two sound sources and hoping that the output of the noise generator doesn't damage the microphone, and vice versa.

Advantages:
  • Teacher microphone is small and light. No wire or belt clip.
  • No echo. Smartphone and Bluetooth approaches had latency that caused echo in the voice.
  • Replaceable batteries. One pair of AAA batteries lasts through 7 hours of school but can be changed if needed.
  • Noise volume can be made loud as necessary.
  • Fits in pocket.
Disadvantages:
  • Only works with the above headphones. It did not work with my other headphones and earbuds. The set above has an impedance of 32 Ohms, whereas the headphones that didn't work were 64 Ohms and the earbuds were 16 Ohms. I'm not sure if that's the issue.
  • Cable connections can be flaky
  • Dangerous volume changes when you turn off one component, described above.
I hope this helps you, or inspires you to build something better! Also, if you find other headphones that work with this setup please let me know.

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