Ministry of Innovation / Business of Technology

Transfer a secret audio message by poking someone with your finger

An inaudible signal becomes audible when touched to the ear.

Disney Research


The microphone converts the voice message into an inaudible signal which is transmitted to the body of the person holding the microphone. The inaudible signal can then be transmitted from that person's body to another person's body through touch. The recorded sound only becomes audible when touching someone else's ear. Their ear canal acts as a sort of speaker, allowing them to listen to a secret finger-transmitted message. The sound can't be heard by anyone else but the person being touched.

The system uses a Shure Super 55 microphone connected to a computer's sound card. The microphone records as soon as it hears a sound over a certain threshold. The computer then creates a loop with the recording which is sent to an amplification driver. The recorded sound signal is then converted into a high voltage, low current inaudible signal. The output of the amplification hardware is linked up to the conductive metal casing of the microphone so that the person holding the microphone will receive the inaudible version of their own message in the shape of a modulated electrostatic field around their skin. When that person then touches another person's ear, the electrostatic field creates a small vibration of the earlobe which, in turn, leads to the ear and the finger, behaving like a speaker.

Enlarge / Not a wet willy.

The prototype is called Ishin-Den-Shin (literally: what the mind thinks, the heart transmits) after the Japanese concept of interpersonal communication through unspoken mutual understanding, inadequately encapsulated by English words like sympathy or telepathy. It was developed by Olivier Bau, Ivan Poupyrev, and Yuri Suzuki.

Suzuki told that the project was born out of a previous project called TeslaTouch, a haptic feedback technology used to add textures to screens. They realized that if the screen could vibrate to create textures it would also be able to create sound. Suzuki explained that Bau felt a similar sort of vibration in a previous generation of MacBook and worked out that by touching the laptop and touching another person it was possible to pass on a sound. "We were looking for some poetic way to send secret information through the body," said Suzuki.

It took a while to get the voltage right to transmit message. "I had so many electric shocks to get the right current and voltage," says Suzuki. Even at the right voltage, the person on the receiving end of the message will feel a tickling sensation.

The research must also have some potential benefit to Disney, so Suzuki, Bau, and Poupyrev considered how it might be used in Disney theme parks to entertain people in queues for rides.

This story originally appeared on Wired UK.

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