From the description provided: It is possible that your brother may be suffering from a psychiatric illness - Most of the psychiatric illnesses get precipitated while under stress (in your brothers case -work). There is a medical term for the suspiciousness that your brother keeps complaining - that is Paranoia — Delusions. The whispering that he complains about is part of his imagination, which could be auditory hallucination (medical term for imaginary sounds). Both of these symptoms could be part of several psychiatric illnesses. Thus, I would strongly urge you to consult a good psychiatrist, as soon as possible, as it is likely that he will have a better outcome with earlier treatment.