We each seem to draw on a different aspect of this passage.
For me this is a promise of discernment. I am the good shepherd; I know my sheep and my sheep know me — just as the Father knows me and I know the Father– and I lay down my life for the sheep.
I posted the passage from Ezekiel. I take this passage to be a claim on the part of John – through Jesus — that Jesus is the fulfillment of the Ezekiel prophecy. The priest and other leaders of Israel have acted like hireling shepherds and thieves and not the shepherds they were called to be. Now God will be their shepherd. And Jesus is using the I am statement to locate that shepherd in his life and ministry.
So how will we know the shepherd’s voice? The same way he knows the Father’s.