speak loudly and strongly
vociferous - loud
A person who is ‘vociferous’ says something in a loud and insistent way. Doing so often causes offence, though it also means that what you have to say is more likely to be heard as you compel attention. It is a formal word that is often used in the context of expressing a demand or complaint.
The workers have recently become more vociferous in their demands and are now threatening to take industrial action.
I have been vociferously opposed to the plan since its inception, so I will be delighted if it is scrapped.
Her vociferation against her critics has crossed the line on a number of occasions.