Hitoshi's Quirk allows him to mind control people who verbally respond to him and as a result they will be forced to do whatever he says. It is shown that he can control more than one person at once.
Whether or not his Quirk activates when someone answers him depends on if he is willing it.
As long as the foe remains silent, this Quirk won't have any effect on them. It's also possible to escape the mind control if the victim is hit by a sufficiently strong physical jolt or through a similar amount of pain.