Before 400 years, Newton shows that a prism could differ a white light into seven different colors of the rainbow. Each color has a different frequency. These type of optimal prism depend upon a physical phenomenon to split light into its constituent frequencies. But now, a prism that exists for sound is discovered. Scientists from École Polytechnique fédérale de Lausanne University have discovered a new kind of acoustic prism. This novel acoustic prism can differ a sound into its element frequencies.
Hervé Lissek and his team at EPFL have invented this acoustic prism that splits sound into its element frequencies. It just uses its physical properties.
This man-made acoustic prism decomposes the sound into its element frequencies. It depends on the physical communication between a sound wave and the prism structure. The acoustic prism then alters the diffusion of each frequency of the sound wave. For this, it does not need computations or electronic components.
The prism looks like a rectangular tube. It actually made up of aluminum, complete with ten, perfectly aligned holes along one side. Each hole causes an air-filled cavity inside the tube. There is a membrane placed between two consecutive cavities.
When sound conducts through the tube at one end, a high-frequency element of the sound of tube breakout through the holes near the source. At the other end, low-frequency element breakout through the holes that are further away. With the dispersion angle, which depends on the wave’s frequency, the sound dispersed.
The membranes are key since they vibrate and transmit the sound to neighboring cavities with a delay that depends on frequency. The delayed sound then leaks through the holes and towards the exterior, dispersing the sound.
The researchers then realize that acoustic prism could be used as an antenna to find the direction of distant sound by simply measuring its frequency. Although, each dispersion angle answers to a specific frequency. It’s enough to measure the main frequency component of an incoming sound to determine where it is coming from, without actually moving the prism.
The principle of the acoustic prism relies on the design of cavities, ducts, and membranes. This can be easily fabricated and miniaturize, possibly causes cost-effective angular sound detection. It does not need to rearrange expensive microphone arrays or moving antennas.
According to scientists, the acoustic prism has applications in sound detection.