Research scientist Ali Aliev, of the University of Texas at Dallas, has determined that the low-frequency sound waves created by carbon nanotube sheets can be used by sonar systems to determine the location, depth, and speed of underwater objects. Aliev and his team also determined that the sheets could be tuned to transmit specific frequencies that would cancel out certain noises… noises such as those that a submarine makes while passing through the water, for instance.
The sheets still needed to be protected from the water. In order to do so, Aliev encapsulated them in thin, flat gas-filled containers with acoustically-transparent windows. As with the air envelopes, the resonance that resulted from the sound waves being generated in such an enclosed space proved to be a benefit – the encapsulated sheets were actually ten times more effective at transmitting low-frequency sound underwater than non-encapsulated sheets.
The optimum arrangement turned out to be a layer of just two separated sheets, which received their electrical pulses alternately instead of simultaneously.