What's the noun for dumber? Here's the word you're looking for.
dumbness
The state of being dumb or mute: that is, of not communicating vocally, whether from selective mutism (refusal to speak) or from an inability to speak.
Muteness, silence; abstention from speech.
Show or gesture without words; pantomime; dumb-show.
“Despite his extensive education and impressive credentials, his repeated errors in simple tasks reflected a profound dumbness that left his colleagues perplexed.”
“The doctor diagnosed her case of dumbness as a result of severe trauma to her vocal cords.”
“If it were solely a matter of the site blooper, then the error might be put down to dumbness and naivety.”
