A locution is a form of private revelation, similar to an apparition, but rather than being seen a locution is heard or received internally. As with all claims of private revelation it is important to be certain that a locution is authentic before any recognition or significance is determined.
The Catechism of the Catholic Church explains,
Throughout the ages, there have been so-called "private" revelations, some of which have been recognized by the authority of the Church. They do not belong, however, to the deposit of faith. It is not their role to improve or complete Christ’s definitive Revelation, but to help live more fully by it in a certain period of history. Guided by the magisterium of the Church, the sensus fidelium knows how to discern and welcome in these revelations whatever constitutes an authentic call of Christ or his saints to the Church.
Christian faith cannot accept "revelations" that claim to surpass or correct the Revelation of which Christ is the fulfillment, as is the case in certain non-Christian religions and also in certain recent sects which base themselves on such "revelations" (CCC 67).
Concerning exorcism, the Catechism states:
When the Church asks publicly and authoritatively in the name of Jesus Christ that a person or object be protected against the power of the Evil One and withdrawn from his dominion, it is called exorcism. Jesus performed exorcisms and from him the Church has received the power and office of exorcizing. In a simple form, exorcism is performed at the celebration of baptism. The solemn exorcism, called "a major exorcism," can be performed only by a priest and with the permission of the bishop. The priest must proceed with prudence, strictly observing the rules established by the Church. Exorcism is directed at the expulsion of demons or to the liberation from demonic possession through the spiritual authority which Jesus entrusted to his Church. Illness, especially psychological illness, is a very different matter; treating this is the concern of medical science. Therefore, before an exorcism is performed, it is important to ascertain that one is dealing with the presence of the Evil One, and not an illness. (CCC 1673)
The Code of Canon Law is clear that only qualified priests with express permission may perform exorcisms: "No one can perform exorcisms legitimately upon the possessed unless he has obtained special and express permission from the local ordinary. The local ordinary is to give this permission only to a presbyter who has piety, knowledge, prudence, and integrity of life" (CIC 1171 §1-2).
The New Commentary on the Code of Canon Law points out that the 1998 Rite of Exorcism reordered this canon. Among the changes, "An exorcist is to be a priest (sacerdos), not a presbyter (presbyterus) as in the canon, which means bishops as well as presbyters may be appointed exorcist" (1405).