Hi, it looks like you are having auditory hallucination. Hallucination is nothing but sensation which is created by your mind. Hallucination could really affect your ears (Hearing), eyes (Visual) or Nose (Smelling). Since you say you are hearing some sound, it may be hearing hallucination. The sound you hear is not a real sound coming from outside, which is created by your mind. This is a symptom for Schizophrenia. Schizophrenia is a serious mental illness which may cause to not find differentiation between real and imaginary. So, I would strongly suggest you to go to a psychiatrist to diagnose the exact problem.