Free speech is so bad I'm arguing for the opposite: especially-taxed speech. "You must be this rich to ride."
All speech should be assumed to be harmful until proven otherwise. Anyone who wishes to speak in the public square should be assumed to be talking out their ass; face-shitting in the common well. As a result they should be charged a cleanup and waste disposal fee.
The wider the audience the speech can reach and the longer it will likely be recorded, the higher the correct exogenous fee. Advertisers especially should be charged out the nose if they want to vandalize the public facades so badly; it's socially harmful and ads look like ass.
Likewise all government broadcasts should come with a tax rebate. If you have to hear it, in any sense of "have" to, they should have to pay you for the privilege of your time. Double minimum wage at the very least. (The joke is there should be no minimum wage, but 2X common minimums is still a good start.)
If your speech really is important then you should be prepared to pay the cost, in literal cash, of speaking it. Maybe you'll get donations from grateful listeners to offset your obligatory fees.
Expensive speech is responsible speech.