When I was very young, around 3, I lost my hearing for a while. We don't really know how long because it didn't seem to bother me. Recently, a friend who went through something similar said the adults in her life knew because she told them she couldn't hear them. Apparently, I didn't. It just never occurred to me that it might be a problem, I guess. My mom says I could still sing on pitch and everything. Weird.
I was learning to read at the time, and my teacher said to my mom that she thought I had some sort of hearing problem. My mom was pretty frustrated with me at this point because she thought I was Evil Rebel Child #1, the One Who Wouldn't Listen to her. After she dropped the unabridged dictionary behind me to test the hypothesis, and I didn't even flinch, she knew there was a problem that wasn't due only to my stubbornness.
So here's the sermon tie in: my mom thought I was choosing not to listen, but the truth was that I couldn't hear. Isn't that maybe a helpful example to explain depravity? It's not that we're choosing not to listen to God, it's that we actually can't hear Him even if we want to. Our sin (like my ear infection gunk), gets in the way and plugs our ears, so even if we want to listen, we can't hear. We can't even tell if someone is talking.
I hesitate to compare the Holy Spirit to tubes in the ears because it's a super imperfect metaphor that dissolves on contact, but, well, some intervention from outside us needs to happen to open up the ear canals, so that we can choose whether to listen. Once I wasn't deaf, I was still certainly accused of selective hearing frequently, but if I wanted to listen, I could.