asses the reason jurror#8 theorizes as to why the old man could not have heard what he described

Described as peaceful and compassionate, Juror 8 is focused on the truth of the case and refuses to give up until the other jurors face that truth. It is through his persuasive abilities that one by one, the other jurors change their initial vote from guilty to not guilty.
In the first vote, Juror 8 is the only one to vote not guilty. He does this not because he really feels that the defendant is necessarily innocent, but for another reason altogether. He votes not guilty because he feels that the group should discuss a case with such serious consequences before deciding. This act shows his desire to contemplate important decisions rather than make an impulsive choice without thinking.
Throughout the discussion, Juror 8 shows the false assumptions made by the evidence presented and illuminates how the testimony of several witnesses does not make sense. For example, he demonstrates how the man in the case who claimed to have heard the boy say he would kill his father could not have heard anything with the L train riding by the apartment building.