Is it really true that the minute after someone dies they are all cured already?
There’s no such thing as a deaf neshomo.
What the neshomo’s range of hearing is
(and/or what it might depend on), I don’t know.
why not nitpick over the fact that he is
davening for the amud a day after his father was niftar
In a case when he is the only available person
who is suited for the job, it is permissible.