Window filters out noise, lets through air.
A new window design created at the Korea Institute of Machinery and Materials lets air flow through freely, while reducing sound by up to 35 decibels.
Their resonance chamber is actually very simple—it consists of two parallel plates of transparent acrylic plastic about 150 millimetres square and separated by 40 millimetres, rather like a section of double-glazing about the size of a paperback book.
This chamber is designed to ensure that any sound resonating inside it acts against the way the same sound compresses the chamber. When this happens the bulk modulus of the entire chamber is negative.
By changing the size of the holes in the window, different frequencies can be filtered out. “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 with fresh air”.