Heard a voice coming from my computer,speakers were off?

Maybe you are suffering from hearing psychosis and therefore had a hallucination that made you hear things. Of course many argue that hearing voices, while is a hallucination, is not necarily attributed to psychosis. Also you may have had an illusion (hallucinations and illusions affect ALL the senses, check wikipedia) and this illusion was cause by the tower noise. Hallucinations do not have external stimuli therefore they are pure products of the mind therefore more serious, while illusions are the misperception of and external stimuli, exaple seeing something differently as it is. I myself have had many sound illusions in my lifetime, the most recent of which is when I thought I heard tv static and a programm going on when in fact it was only the rain.