The discourses are issued both for being heard and for being used for hearing your own discourse. In the second case, it is clearly intended their understanding: we cannot understand something alien to us otherwise than by rethinking it through our own mental capacities and acquisitions.
As it is testified by the experience of listening to the music (we do not listen only musical notes), the hearing brings to us more than the plain meaning of the discourses.
Evidently, there are all the elements of rhetoric and of the context in which the discourse was held.
Still more, it is the indefinite feeling of meeting something different from us. Maybe as a consequence of the Darwinian struggle for existence, the human individual who is preoccupied with his personal existence and strives for his social prestige needs also to find something different from him on which base he can build his personality. In loosely terms, such a reality different from him is the world.
Though we all live into the world, we rarely know it as something different from us. Therefore, that sense of receiving something different from us only by hearing encourages us to believe even into the discourses which are not really understood. Thus, the apparent slavish situation of someone who embraces misunderstood discourses is an act of self-esteem or the result of a strong wish for self-affirmation into the world.
Nonetheless, many skilful speakers are interested rather in producing discourses for hearing and not for understanding. Moreover, the speakers hear themselves and have the same sense of conquering a reality as different from them as the world. Thus, there are many well intentioned preachers, but they are affected from that natural and common need of finding something different from us.