Trying to concentrate in a busy coworking space? Suffering through a long flight with a screaming baby across the aisle? Annoying environments compel most of us to plug headphones into a speaker jack and (attempt to) leave the world behind. But the cut rate earbuds that came with your smartphone hardly deliver the kind of sound you can expect from the world’s newest graphene invention.
Graphene has extremely low mass density and high mechanical strength, key qualities for efficient wide-frequency-response electrostatic audio speaker design. This is what led researchers at the University of California, Berkeley, to create the first ever pair of graphene-based earphones. And according to reports, even the crude prototype delivers incredible sound.
Most loudspeakers work using a diaphragm that creates pressure waves in air by mechanically vibrating. The ear-sized graphene audio speakers do this too, by sandwiching a 30nm-thick, 7mm-wide sheet of graphene between two silicon electrodes. What extraordinary is that this crude construction delivered amazing sound upon first testing.
“The speaker/earphone is straightforward in design and operation and has excellent frequency response across the entire audio frequency range (20HZ – 20kHz), with performance matching or surpassing commercially available audio earphones,” write the study’s authors, Qin Zhou and Alex Zettl.
“The diaphragm in any speaker is essentially a simple harmonic oscillator with an inherent mass and restoring force that determine the way it vibrates at different frequencies,” explains Technology Review. “Most diaphragms need to be damped to broaden the range of frequencies over which they perform.” But this dampening process adds undesired bulk, cost and power inefficiencies.
Using graphene, the diaphragm can be made very light and thin without increased fragility. “Even without optimization, the speaker is able to produce excellent frequency response across the whole audible region (20 Hz~20 KHz), comparable or superior to performance of conventional-design commercial counterparts,” says the team. Best of all, the air-damped graphene converts most of its energy into sound and so is extremely energy efficient.