«العقل: وهو نور يدرك به ما لا يدركه الحواس»
Reason is the faculty through which one understands what the senses alone do not disclose.
The narrator must have the competence to grasp what is being communicated. The text requires a mature degree of reason, described as the reason of an adult.
A person might hear sounds without reliably understanding the meaning and context. This is why physical hearing alone is not sufficient for sound transmission.