Passage: The components of a mechanical filter are all directly analogous to the various elements found in electrical circuits.  The mechanical elements obey mathematical functions which are identical to their corresponding electrical elements.  This makes it possible to apply electrical network analysis and filter design methods to mechanical filters.  Electrical theory has developed a large library of mathematical forms that produce useful filter frequency responses and the mechanical filter designer is able to make direct use of these.  It is only necessary to set the mechanical components to appropriate values to produce a filter with an identical response to the electrical counterpart.

Question: Who employs the libraries of electrical theory mathematics?
the mechanical filter designer