Source : Webster's Revised Unabridged Dictionary (1913)

Plangency \Plan"gen*cy\, n.
   The quality or state of being plangent; a beating sound. [R.]

Source : WordNet®

plangency
     n : having the character of a loud deep sound; the quality of
         being resonant [syn: {resonance}, {reverberance}, {ringing},
          {sonorousness}, {sonority}, {vibrancy}]