Sound horns in LEAF wall

It looks like a giant version of a sound system, and that is precisely what it is. ESA’s Large European Acoustic Facility (LEAF) subjects satellites to the same noise a launcher produces as it takes off and flies through the atmosphere.

LEAF is an integral part of ESA’s test centre in Noordwijk, the Netherlands, a collection of spaceflight simulation facilities under a single roof. One wall of the chamber – which stands 11 m wide by 9 m deep and 16.4 m high – is embedded with a set of enormous sound horns. Nitrogen shot through the horns can produce a range of noise up to more than 154 decibels, like standing close to multiple jets taking off.

As a safety feature, LEAF can operate only once all the doors are closed. Steel-reinforced concrete walls safely contain its noise, coated with epoxy resin to reflect noise to produce a uniform sound field within the chamber. The chamber itself is supported on rubber bearing pads to isolate it from its surroundings.