The Collaborative International Dictionary of English v.0.48:

Obstreperous \Ob*strep"er*ous\, a. [L. obstreperus, from
   obstrepere to make a noise at; ob (see Ob-) + strepere to
   make a noise.]
   1. Attended by, or making, a loud and tumultuous noise;
      clamorous; noisy; vociferous. "The obstreperous city."
      --Wordsworth. "Obstreperous approbation." --Addison.
      [1913 Webster]

            Beating the air with their obstreperous beaks. --B.
                                                  Jonson.
      [1913 Webster]

   2. Resistant to control; unruly.
      [PJC] -- Ob*strep"er*ous*ly, adv. --
      Ob*strep"er*ous*ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

obstreperously
    adv 1: in manner that attracts attention; "obstreperously, he
           demanded to get service" [syn: obstreperously,
           loudly, clamorously]