Jesus’s flock are not the only ones that make up his church,yet those that hear his voice are:

Luke 12:32

Do not be afraid, little flock, for your Father is pleased to give you the kingdom.

Jesus is the good shepherd and his sheep know him and he knows his sheep,he calls them by name and leads them out:

John 10:2-3 & 14

The one who enters by the gate is the shepherd of the sheep.

The gatekeeper opens the gate for him, and the sheep listen to his voice. He calls his own sheep by name and leads them out.

I am the good shepherd. I know my own and my own know me,

Jesus has other sheep not of the sheep pen he oversaw on earth and He must bring them also and they too will listen to His voice and there shall be one flock and one shepherd:

John 10:16

I have other sheep that are not of this sheep pen. I must bring them also. They too will listen to my voice, and there shall be one flock and one shepherd.