Mindspeakers are people with the ability to hear other people's thoughts. They can also commuicate to other people by thinking what they want to say to someone into that person's mind. It only takes one mindspeaker to carry on a thought conversation, since the mindspeaker can place his/her thoughts in the other person's mind, as well as read that person's response thoughts.
A person can block a mindspeaker from reading his/her thoughts. To stop a particullarly evil and powerful person, such as Risto, from reading their thoughts, a simple prayer to Wulder for protection blocks them effectively.