Most of us had the experience to sit in a room focused on something we do, such as reading or writing and then hear the clock stop, whereas before we hadn’t noticed that beating. From the moment the clock stopped, there was nothing else to hear, but, previously, the brainstem filtered the harmless sound of repetitive clock beats, so the sound would not reach the level of perception. This is more difficult to happen with an irregularly dripping tap and can be a source of constant annoyance, partly because we expect the next drop will fall and display greater stimulation to the brainstem when the expected sound is not coming.
Depending on one’s personality, either learns to tolerate this irregular situation or is irritated and does something about it. The same thing happens when you buy a new refrigerator. At first the noise of the machine when it starts working and then stops in an irregular manner and its tone of operation can be annoying. In the end, however, almost everyone gets used to it and it ceases to be a problem.
The brainstem has some editing capabilities of the incoming audio messages. It may withhold any messages that are considered harmless in light of past experience. The early warning function and additional emotional factors associated with unexplained or unexpected sounds are not presented, so the message may ultimately not get to become conscious.
People at the top of this complex system of survival, also have a “higher level” database, which gives them sensations, feelings, thoughts and emotions, which in turn interact and affect the lower centers. The situation is structured in such a way that there is an “internal conflict” with any slightly abnormal electrical activity in the system of hearing provoking fear and anxiety from the high-level database. This causes a corresponding activation of the brainstem and therefore a nuisance. This happens regardless of whether the sounds are internal or external.