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What is SpeakFree?

SpeakFree is a microphone jammer. It makes it harder for microphones to pick up your private conversations by emitting loud and random noise.

Is this just a white noise generator?

Not quite. We specifically generate random noise in the range of the human voice (300-3400 Hz), making it more difficult to filter out than white noise.

As of writing, our technique involves generating ten random sine waves within the vocal frequency range, and layering them over each other to produce noise. At frequent intervals we swap out one of the waves with a new random wave to keep the noise unpredictable.

How effective is it?

From our own testing, if you speak quietly with SpeakFree running next to you and another phone recording audio from ten feet away, the remote phone will pick up that someone is talking, but can only make out an occasional word.

Adding additional phones running SpeakFree, or plugging a phone in to speakers, will improve effectiveness.


We cannot guarantee that SpeakFree will make your voice undetectable. Too low a volume, too excellent a microphone, or too skilled a sound engineer may allow your conversation to be extracted. SpeakFree will make the work of the surveillance state harder, and serves as a symbol of resistance.

Additionally, SpeakFree produces loud noise that may damage hearing or equipment. It is the responsibility of the user to set a safe volume level. The Daylighting Society and associated developers assume no responsibility for the well being of speakers and ears effected by SpeakFree.

Who are you?

The Daylighting Society is a non-profit devoted to protecting the public from surveillance and censorship through developing positive technology.

I have more questions or suggestions

That’s great! Please write to us at