What, if any, scientific value do global soundscapes have?
Remote sensing using passive sonar and seismograms, which are
  acoustic or near-acoustic signals, works on the principle of the
  inverse problem. While the object or phenomenon of interest (the
  state) may not be directly measured, there exists some other variable
  that can be detected and measured (the observation), which may be
  related to the object of interest through the use of a data-derived
  computer model.
  
  Soundscape ecology is the study of sound within a landscape and
  its effect on organisms. Sounds may be generated by organisms
  (biophony), by the physical environment (geophony), or by humans
  (anthrophony). Soundscape ecologists seek to understand how these
  different sound sources interact across spatial scales and through
  time. Variation in soundscapes may have wide-ranging ecological
  effects as organisms often obtain information from environmental
  sounds. Soundscape ecologists use recording devices, audio tools, and
  elements of traditional ecological analyses to study soundscape
  structure. Increasingly, anthrophony, sometimes referred to in older,
  more archaic terminology as anthropogenic noise dominates soundscapes,
  and this type of noise pollution or disturbance has a negative impact
  on a wide range of organisms. The preservation of natural soundscapes
  is now a recognized conservation goal.
  
  Source: Wikipedia links referenced above.