Läslo Evers

Inaudible Sounds

If we were able to hear the inaudible symphony, as Läslo Evers calls the omnipresent rumble of low frequency sounds, we would experience an unpleasant tumultuousness. Fortunately, the infrasonic sounds produced by waves, volcanos, breaking icebergs, elephants, and whales are undetectable for the human ear.

Läslo Evers, who works at the Royal Netherlands Meteorological Institute (KNMI), however, is a regular listener to this natural symphony. It all started in 1998 when the geophysicist was asked to monitor the sonic booms of military fighters of the Royal Netherlands Air Force. Evers became project manager and constructed a 16-element microbarometer array on Deelen Air Force base to measure infrasound from jet-fighters flying supersonically above the North Sea.

As Evers registered additional infrasonic waves, he was drawn into studies on source identification from meteors, volcanoes, oceanic waves, and large explosions. Next, he engaged in research into the influence of the upper atmosphere on these sounds and applications in astronomical science. Based on this work, in 2008 Läslo received his PhD degree in Aerospace Engineering and Applied Sciences of the Delft University of Technology.

In his research, infrasound is applied as a verification technique for the Comprehensive Nuclear-Test-Ban Treaty (CTBT) and a worldwide network of 60 infrasound arrays is being constructed to detect infrasound from nuclear tests. Evers, who now combines his work at KNMI with an associate professorship at TU Delft, is currently most involved in finding ways to use infrasound to determine circumstances in the upper layers of the atmosphere.