The word you are looking for is an aspect of hearing called selective listening.
Hearing is a physiological process which requires only the proper functioning of the hearing apparatus, which includes the outer-, middle-, and inner ear. See the picture below.
When sound is received at the inner ear, cochlear nerve fibers are stimulated and send electrical impulses to the auditory cortex in the temporal lobe of the brain, where with the help of several feedback loops along the way, sound is divided into non-speech and speech components.
Non-speech elements consist of frequency, intensity, and sound location, whereas speech elements include phonemes or consonants, tone, semantics, and syntax (see here).
To make matters even more complicated, since the cochlear nerve does not terminate in the auditory cortex but extends to the cochlear nuclear complex in the brain stem, auditory information passes to a midbrain region, the inferior colliculus, and a forebrain region, the medial geniculate nucleus of the thalamus. Both regions send auditory information up to the primary auditory cortex.
When a person is simply hearing you, they are short-circuiting, so to speak, the more complex process of speech interpretation. We call that short-circuiting process selective listening. A teenager, for example, may hear his mother not once but several times asking him to take out the garbage, but because of selective listening the mother’s message does not get processed completely. Hence, the message is not acted upon, or obeyed.
Similarly, when a coworker or friend is yammering at you while you are doing something else which requires a fairly high level of cognitive functioning, you can choose to filter out the speech content and its meaning so as to be able to continue what you’re doing.
What the speaker who is being “tuned out” needs to do at that point is to get the listener’s full attention, and then with eye-to-eye directness arrange to talk at another time and/or place so that effective speaking and listening (i.e., communication) can take place.