New Type of Window Muffles Outside Noise but Lets in Fresh Air

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Cool night air is great when you’re sleeping, but outside noise can prevent you from having uninterrupted rest. To let the air in, but keep the noise out, scientists from South Korea came up with windows that have acoustic suppression properties with holes to let fresh air in.

air transparent soundproof window diagram

Professor Sang-Hoon Kim of Mokpo National Maritime University and Professor Seong-Hyun Lee of Korea Institute of Machinery and Materials created the air-transparent soundproof window out of several clever “blocks”. Individual blocks measure 150x150x40 mm with either a 20 mm or a 50 mm diameter hole in its center.

Each block is a sound resonance chamber, with sound waves bouncing around inside canceling each other out. Experiments showed that the 20 mm diameter holes are effective at suppressing noise across all frequencies (red), while the 50 mm diameter holes are most effective for noise in the 700-2200 Hz range (blue). That tends to be the range of artificial sounds, leaving the natural sounds in the 0-500 Hz range largely undisturbed.

transparent soundproof windows frequency chart

After sending sound waves of 80 decibels (sound louder than a vacuum cleaner) through both windows, they discovered that the holes reduced sound level by about 30 to 35 decibels (to the levels of a quiet suburb).

Varying the size of the holes makes the windows tunable, meaning that they will suppress sounds of one range of frequencies, but not another. “For example, if we are in a combined area of sounds from sea waves of low frequency and noises from machine operating at a high frequency, we can hear only the sounds from sea waves” say Kima and Lee.

Watch the YouTube video above made by Sang-Hoon Kim to understand how effectively a window like this can block out the irritating traffic noise outside – suppressing the noise pollution you would otherwise experience.

varying designs of the sound poof window

Visionaries + Movers

Sang-Hoon Kim + Seong-Hyun Lee

Photos via: Mokpo National Maritime University

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