Justin Bieber -- Don't Blame My Hotness ... For Your Hearing Loss

You can't blame Justin Bieber if his fans scream so damn loud you go deaf, and you definitely can't sue him over it either ... at least according to legal docs filed by Justin's lawyers.

TMZ broke the story ... a mom named Stacey Betts slapped Bieber with a $9.23 million lawsuit ... claiming her hearing was severely damaged at a 2010 concert when the Biebs "enticed the crowd" into a screaming frenzy.

Now Justin's firing back, claiming Betts' lawsuit is missing a few things -- like facts.

According to the documents, there's no way JB could have known "pointing to a crowd" would cause a so-called "sound blast" -- and Betts' suit also fails to allege Bieber has any duty to stop fans from making noise.