verb

reproduce (a message, sound, or transmission) in a confused and distorted way.

the connection was awful and kept garbling his voice

mix up,muddle,jumble,confuse,blur,slur,obscure,distort,twist,twist around,warp,misstate,misquote,misreport,misrepresent,mistranslate,misinterpret,misconstrue,tamper with,tinker with,change,alter,doctor,falsify,pervert,corrupt,adulterate,misarticulate,misrender