Took the words right out of my mouth

Japanese-made SpeechJammer gun aims, points, and leaves people tongue-tied

Imagine that, while you were speaking, someone pointed a device in your direction that literally left you speechless. Apparently, such a contraption exists.

Back in 2012 two Japanese research scientists, Kazutaka Kurihara and Koji Tsukada, designed a gun-shaped device they call the SpeechJammer that can be used to disturb people’s speech, make them stutter or make them stop talking altogether.

By using a directional microphone, a directional speaker, and a distance sensor, the SpeechJammer gun trips up its target by playing back their own voice to them at a slight delay of around 200 milliseconds. Putting together each of these pieces on top of a black acrylic case, with a trigger added below, allows the device to resemble a gun.

The science behind this device’s success is the use of artificial speech disturbance with Delayed Auditory Feedback (DAF).

As Kurihara and Tsukada write in their paper, aptly titled SpeechJammer: A System Utilizing Artificial Speech Disturbance with Delayed Auditory Feedback, “[w]e report a system that jams remote people’s speech using Delayed Auditory Feedback, a well-studied method involving the human auditory system. This effect can disturb people without any physical discomfort, and disappears immediately [when] the speaking stops. Furthermore, this effect does not involve anyone but the speaker.”

In essence, all it takes to disrupt someone’s speech is relaying their own voice back to them at a slight delay.

Since our brain is used to processing only one speaker’s voice at a time, feeding a second voice — which is our own — at the same time confuses the brain, induces mental stress, and therefore leaves us tongue-tied and unable to speak properly.

“In our preliminary study, we dealt with ‘reading news aloud’ and ‘spontaneous monologue’ as the speech contexts,” write Kurihara and Tsukada. “From the results, we observed a tendency for speech jamming to occur more frequently in the ‘reading news aloud’ context than in the ‘spontaneous monologue’ context. Further, it is obvious that speech jamming never occurs when meaningless sound sequences such as ‘Ahhh’ are uttered over a long time period.”

DAF devices, it turns out, have been used for decades as a technique to aid people with stuttering issues, according to the researchers.

In a study conducted for the International Journal of Language & Communication Disorders back in 2003, nine stuttering individuals between the ages of 18 and 45 participated in a three-month investigation to test the effect of repeated exposure to DAF to improve their speech fluency.

At the end of the three-month period, the percentage of stuttered words during non-altered feedback, before and after repeated exposure to DAF, showed significantly less stuttering after the repeated exposure to DAF.

Given these results, if both a non-stutterer and a stutterer were to be exposed to the SpeechJammer or any DAF device, the stutterer would actually be more likely to speak clearly than the non-stutterer.

Although the SpeechJammer gun is still a prototype, anyone can build their own version at home. For people willing to test it out themselves, a Speech Jammer app is available for iPhone and Androids to try and play around with.

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