Sound of Silence

An “acoustic metamaterial” was recently demonstrated that can attenuate sound by up to 94 percent. More importantly, the material is permeable to airflow as well as light, making it suitable for many applications where traditional mufflers are not.

Most acoustic materials (such as foam) absorb sound and turn it into heat; however, they generally need to block the entire opening in order to function efficiently. The new material consists of a series of 3D printed rings that work by capturing sound and reflecting it back toward the source. The secret is in the shape, which is mathematically designed for specific frequencies and can be tailored to a wide range of sounds.

For example, MRI machines could be fitted with silencers to make scanning more comfortable for patients. Because the rings are open, HVAC systems and ductwork could be fitted with the material to mute the sound of fans and compressors. They could even be stacked to create soundproof yet see-through walls in open office areas, factories and airplanes.