 The use of "Dutch" and "Walloon" to describe these two supposed types of finches has been suggested to refer to a simple difference in calling not literally linked to either the Flemish or Walloon communities of Belgium, and some linguists even suggest that "Walloon" simply means "foreign".While minute regional differences (a.k.a.dialects) in song have been observed in the chaffinch (also within Belgium), the differences have only been reliably distinguishable by the use of sonograms.