(n.) The quality or state of being voluble (in any of the senses of the adjective).

big mouth candor communicativeness conversableness effusion effusiveness flow of words flowing tongue fluency fluent tongue flux de bouche flux de paroles flux of words frankness garrulity garrulousness gassiness gift of gab glibness gregariousness gush gushiness long-windedness loose tongue loquaciousness loquacity openness prolixity slush sociability spate of words talkativeness verbosity windiness