Jesus was responding to the demands of "the Jews," establishment-types, probably leaders, who were upset at Jesus' indirectness about whether he is the Messiah. Jesus insisted that it was quite clear from his works (not simply miracles as the NIV improperly translates) if not from his statements and teachings.
However, those who know his voice know precisely what he is doing and what he is about. They are like sheep who hearken to the voice of the shepherd. That statement in itself is pretty loaded. Those who don't get it aren't listening; they're waiting to entrap and convict, to get Jesus out of the picture.
We use filters to decide what gets our attention and what isn't worth it. They're very effective. But we need to be deliberate if we're looking to set the Lord's voice and the Kingdom's agenda as a priority.
Peter gives a lesson in that as he is called to Joppa where a saintly figure has died. Upon arrival, he is confrotned by the wailing mourners. They are a witness to death, not a resurrection witness. He shoos them away and devotes himself to prayer. He sets his priority and connects with the voice that empowered him with the promise of life. From that spirit, he brings the deceased to life once again.
There is a whole lot more in the sermon which you can check out with the sermon video or by downloading the text at the link below the video panel.