Footfalls for Phone Calls

New tech could power portable gadgets with every step

3 min read

7 September 2011—As smartphones and other portable gadgets push the limits of handheld computing, their hunger for electricity has only increased—with no end in sight. A new technology aims to address this issue, not by seeking bigger and better batteries but by looking instead to the shoes on our feet.

When we walk, our bodies create up to 40 watts of mechanical power as heat when our feet strike the ground. A special electricity-generating cushion placed inside the soles of a regular pair of shoes can transform some of that footfall power into several watts of electricity. Over the course of a single day, the generated energy, which gets stored in a small battery in the sole, provides enough electricity for a pedestrian to extend her smartphone’s battery life, for a soldier to augment his portable power needs in the field, or for someone in a developing nation without an electrical grid to power a night’s worth of LED home light use.

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Deep Learning Could Bring the Concert Experience Home

The century-old quest for truly realistic sound production is finally paying off

12 min read
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Image containing multiple aspects such as instruments and left and right open hands.
Stuart Bradford
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Now that recorded sound has become ubiquitous, we hardly think about it. From our smartphones, smart speakers, TVs, radios, disc players, and car sound systems, it’s an enduring and enjoyable presence in our lives. In 2017, a survey by the polling firm Nielsen suggested that some 90 percent of the U.S. population listens to music regularly and that, on average, they do so 32 hours per week.

Behind this free-flowing pleasure are enormous industries applying technology to the long-standing goal of reproducing sound with the greatest possible realism. From Edison’s phonograph and the horn speakers of the 1880s, successive generations of engineers in pursuit of this ideal invented and exploited countless technologies: triode vacuum tubes, dynamic loudspeakers, magnetic phonograph cartridges, solid-state amplifier circuits in scores of different topologies, electrostatic speakers, optical discs, stereo, and surround sound. And over the past five decades, digital technologies, like audio compression and streaming, have transformed the music industry.

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