Acoustic Energy Harvesters Gaining Volume

So far, harvesters can get milliwatts of electricity from sound. That might be enough for some things

3 min read

26 April 2011—Where some people hear noise, Jeong Ho You hears energy. "Acoustic energy is everywhere," he says. And with the help of a tiny resonating chamber, he wants to trap some of that energy and convert it into a low-amperage current for use in small electronic devices. You, a mechanical engineer at Southern Methodist University, in Dallas, will be presenting the results of a computer simulation of a resonating chamber design at next month’s Acoustical Society of America meeting in Seattle. He then plans to build a device to see how his idea holds up in the lab.

The siren song of acoustic energy is soft—so soft that some researchers don’t think it’s worth the trouble to harvest it. Mark Sheplak, a mechanical engineer at the University of Florida, in Gainesville, who helped build an acoustic energy harvester for use in a NASA jet engine research project, says, "A lot of people wrote it off because there are just a few applications where there’s enough sound to be useful." The problem is that acoustic energy is not very dense: The sound of a crowd in full roar at London’s Wembley Stadium would provide only enough energy to fry an egg, Sheplak estimates.

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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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