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):

obstreperous
    adj 1: noisily and stubbornly defiant; "obstreperous boys"
    2: boisterously and noisily aggressive; "kept up an obstreperous
       clamor"

Moby Thesaurus II by Grady Ward, 1.0:

87 Moby Thesaurus words for "obstreperous":
   bawling, beyond control, blaring, blatant, blatting, blustering,
   boanergean, boisterous, brassy, brawling, brazen, breachy, clamant,
   clamorous, clamoursome, clanging, clangorous, clattery,
   contumacious, crying, defiant, disorderly, fractious,
   impatient of control, incorrigible, indocile, indomitable,
   insuppressible, intractable, irrepressible, loud, loudmouthed,
   mafficking, multivocal, naughty, noiseful, noisy, openmouthed,
   ornery, out of control, out of hand, rackety, rambunctious,
   rampant, raucous, recalcitrant, refractory, resistant, resisting,
   restive, revolutionary, riotous, rip-roaring, roisterous, rowdy,
   rumbustious, screaming, shouting, shrewish, strepitant, strepitous,
   strident, tempestuous, terrorist, tumultuous, turbulent,
   unbiddable, unbridled, uncontrollable, uncontrolled, undisciplined,
   ungovernable, unmalleable, unmanageable, unmoldable, unrestrained,
   unruly, unsubmissive, uproarious, vociferant, vociferating,
   vociferous, wild, yammering, yapping, yelling, yelping