Sounds that are well audible in the air are almost indistinguishable for those who are under water. Solve this problem with a special membrane suggested by the authors of the article accepted for publication in the journal Physical Review Letters.
Sound waves lose almost all their energy (99.9%) when passing from the air to the water. Because of this, for example, a diver almost does not hear people talking in a boat next to him. The authors described a design that can be placed on the water surface and thus improve the conductivity of sound by 160 times.
Developed by scientists, the devices are pieces of latex, the size of poker chips, stretched on aluminum frames, connected to the membrane on a plastic ring. This design operates in much the same way as an anti-reflective lens coating. Membranes with different properties reduce the reflection of sound waves and pass more energy through the boundary of water and air.
The scientists tried their invention in the range available to the person’s ear. Measurements showed that, when hit in water, sound waves lost only 6% of energy (without a membrane – 28%). The authors of the work note that with the use of their device, the conversation in the boat will be heard by the diver in much the same way as the person above the water, usually it is more like a whisper in the library.
The creators of the membrane expect that their device will come in handy when organizing deep-sea scientific expeditions or search operations. It can also be adapted for medical purposes: the membrane can improve the quality of images obtained with ultrasound.