Justin Bieber Responds To Concert Hearing Damage Claim

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.