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David Zax

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That's a Stretch: All-Rubber Speakers

“Smart rubber” speakers save on width without skimping on bass.

  • October 23, 2012

Diginfo reports on a curious new technology from Tokai Rubber Industries: the first all-rubber speaker.

Besides the fact that they’re visually arresting—the video below will make you do a double take—why should we care about rubber speakers? For one thing, says a Tokai rep, these could be ultrathin speakers that nonetheless can pack a whopping bass line. Traditional thin speakers like the ones in your smartphone aren’t so good at hitting the lower frequencies. “It’s the first speaker of this kind in the world,” boasts the Tokai rep here:

A few other neat concepts mentioned in that video: the ultra-flexibility of a rubber speakers means that you could potentially build it into nontraditional objects, like chairs. Imagine if your very couch was upholstered with a next-gen speaker. (Seems like it might double as a massage chair, too.)

The technological trick behind so-called “smart rubber” is to make the material conduct electricity, something Tokai achieves by sticking nonconductive rubber in between two rubber electrodes. Applying voltage between those electrodes generates static electricity, which can then be used to manipulate the rubber sheet. The resulting motion of the sheet produces sound waves. “Each type of rubber has to be flexible, and the insulating rubber mustn’t change its resistance when it expands,” Tokai told Diginfo. “That’s a key technology in this speaker.”

Tokai seems to specialize in “stretching” our conception of rubber, so to speak. They also made rubber touch sensors. Curiously, this rubber speaker concept emerged from another line of research from Tokia: the project of making smart rubber artificial muscles.

Got rubber on the brain? Dig into our archives for more. Did you know that Mesoamericans used rubber balls as far back as 1,600 BCE? (See “Rubber’s History Stretches Way Back.”) Or that the manufacturers of our next generation of tires might be—bacteria? (See “Rubber from Microbes.”)

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