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Noise Control in Space

By April 6, 2015May 26th, 2016Noise Control

Space is indeed a vacuum, and cannot support sound waves.  So how can a spacecraft have noise problems on orbit?  Crewed orbital vehicles carry an atmosphere with them, and any equipment that’s noisy on earth can be just as noisy in space.

Two major sources of on-orbit noise are life-support systems and computerized equipment, both of which use fans to move air.  The individual contributions from each equipment item don’t need to be large for a problem to occur: the large number of items combined with the cramped quarters lead to a potentially noisy environment.

The usual earthbound coping mechanisms are impractical:

  • Move farther away from the noise source
  • Create sound barriers
  • Wear earplugs or muffs

Gravity places an extreme penalty on additional launch mass, so spacecraft are no larger and no heavier than necessary.  That means there’s no “farther away” and noise barriers (often heavy) are unwelcome passengers.  Furthermore because work, time-off, and sleep take place in the same environment, muffs would have to be worn 24/7.

NASA astronauts complained about noise on the International Space Station.  The sound levels were well below hearing conservation levels: the problem was speech communication.  Many activities in the laboratory modules require coordination between crewmembers and the astronauts: the accumulated noise generated by the experimental hardware was sufficient to cause astronauts to turn or move towards each other to communicate effectively.  In other words, excessive noise was an obstacle to mission effectiveness.

Nelson Acoustics provided services to NASA related to demonstrating the speech communication challenge, intrinsically quiet design of hardware, testing engineering mockups and actual flight experimental equipment, as well as proposed noise management strategies for deep-space missions.

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