So the discussion continues although the question shifts from “when” to “how”.
Does the recitation of the Sh’ma have to be audible? Again R’ Meir and R’ Yehudah disagree. R’ Meir says it must be audible or it isn’t valid; R’ Yehudah says that an inaudible recitation is valid but only “after the fact”, the assumption being that if you knew at the outset that it needed to be audible you would have taken greater care to perform it audibly.
But what about a recitation that is audible in one’s heart only? It is not valid although the Sh’ma itself says that the words should be “upon your heart”. Hmmmm.
Accepting the yoke of heaven’s sovereignty is a big job. The gemara states that R’ Chiya bar Abba said in the name of R’ Yochanan that a person who gets up, relieves himself, washes his hands, puts on tefillen, and then recites the Sh’ma is the same as one who builds an altar and offers a sacrifice.
Let’s be careful though that we don’t turn that alter into an idol and make things so difficult that a regular person could not ever succeed. So for now I’m with R’ Yehudah although you might not always be able to hear me.