Noise cancelling megaphone

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Project Noise Cancelling Megaphone
Status Abandoned
Contact Walter
Last Update 2016-02-18


First, it is not really a proper noise cancelling megaphone, but more of a speech/music-jamming one. Have a troublesome source of sound shut of by broadcasting the sounds back, but only perceptably delayed.

Ever encountered those useless type to cheap to buy a headset for their mp3-playing mobile? To add insult to injury their taste in music tends to be in the 'atrocious' part of the musical-taste-spectrum, often involving autotuned hip hop. This might be a solution.

Combine a directional microphone with a megaphone and a Raspberry Pi for the signal processing. Have the megaphone broadcast the sound collected through the directional microphone just a few milliseconds out of sync back to the source of your annoyance. Also works great on yapping dogs.


  • Megaphone (about 30 USD on eBay)
  • Directional microphone (also about 30 USD on eBay)
  • Raspberry Pi, model A or B (model A goes supposedly for about 25 USD ex tax & shipping)

Easy part

  • Integrating the hardware, probably involving a custom microphone holder (probably 3D-printer) and some epoxy
  • Weather- and fool-proof RasPi case

Hard part

  • Getting a RasPi Model A, they're not available yet
  • Doing the signal processing software, has anyone ported PureData to ARM yet?

Oh yes, they have:!

So if you have experience with Pure Data ( this may actually be trivial.

Project info

Actually this is not so much a project as a concept. I'm not going to execute it, but if anyone is willing to actually do it I might help funding the components. If you do: please have it airbrushed appropriately and have it available for events such as hacker camps and Chaos Congress.

Notes by smeding

I don't want to change the project myself, but here's my two cents: It's probably far cheaper and easier to implement the wanted effect using analogue electronics such as op-amps. It removes a lot of complexity from the signal processing chain, which should make it easier to get repeatable, wanted results.