Scientists and the medical community tend to label the hearing of sounds and voices that aren’t physically there as auditory hallucinations. Without any diagnosis of mental illness, hearing sounds that aren’t there is quite common in the ordinary population. In fact, research has found that one in twenty people will hear a voice that isn’t there at least once in there lives. Of course, you heard a knocking ‘sound’. Hearing sounds has been linked to random firing of neurons in certain areas of the brain. With hearing sounds, researchers have found that areas of the left superior temporal gyrus of the brain is active, as well as other areas of the brain. If the sound is repeated, it could be that certain triggers will cause the neurons in that part of the brain to become active and hence you hear the knocking.
Hearing sounds and voices have been part of human culture since ancient times, so I wouldn’t be too worried if I were you. In fact, ancient meditators from India and Japan have a meditation technique called the Sound Seers Gateway, whereby on the road to enlightenment at certain stages meditators will hear certain mystical sounds such as the tinkling of bells, or the sound of a bamboo flute. As you know, a ‘seer’ also known as an ‘oracle’ is a mystical person who has communication with the Gods in ancient Greek culture to divine the future.
But sticking to modern scientific research, hearing the knocking is just a random activation of certain parts of the brain, and if repeated, a certain trigger causes that activation to occur each time.
If you become aware of the accompanying thought and emotion you have when you hear the knocking, it could be a clue to the trigger for the knocking. Also, lack of sleep, high stress, or even too much caffeine could trigger hearing the knocking.
As for dreaming about the knocking, it would be interesting to know the content of your dream? Knocking could be your mind searching for answers to a question that you have, with yourself knocking on a door, or it could be a new experience wanting to enter your life.
Often, dream interpretation starts with recording the dream as soon as you awaken, and then looking for recurring images, accompanying emotions, and the narrative behind the dream. As for hearing knocking in the dream, all five senses can be activated in your dreams, including taste, touch, sound, sight and scent.