6th level ability seems ...sad. Considering several abilities/classes give Telepathy, Thieves Cant, or Druidic out of the gate, this should probably be a ribbon 3rd level ability. It isn't more powerful than say, message.
I would suggest some illusion-based ability at 6th - the ability to "mime" an object into existence or defy physics/logic with an interesting ability. An ability to render others unable to make noise might be interesting as well. <Edit, missed this possible in Dumbstruck Enactment. However, for a 14th level ability, it seems weak as it's replicating either Web or Silence, usable once per long rest. It should either be usable more often or strengthened up to a once-a-day 7th level spell quality - maybe restrained + silenced + ongoing psychic damage if maintained>.
Hypnotic Performance might be a better name for Dumbstruck Enactment.