In paragraph 3, Mr. Abernathy's voice "sounded like a shovel scraping concrete." What does this comparison suggest?

The ice storm came on a Tuesday night, and by Wednesday morning our whole street in Denton had turned to glass. Every branch, every mailbox, every blade of grass wore a clear, hard coat. It was beautiful for about an hour. Then the power went out.

By afternoon, the house was so cold that I could see my breath in the kitchen. Mom wrapped my little brother, Theo, in two blankets on the couch. Our stove was electric, so we ate cold cereal for lunch and peanut butter sandwiches for dinner and pretended it was an adventure.

Across the street lived Mr. Abernathy. In the three years we had lived on Hackberry Lane, I had heard him speak maybe five times, usually to tell kids to stay off his lawn. His voice sounded like a shovel scraping concrete. I kept my distance.

On Thursday morning, someone knocked on our door. It was Mr. Abernathy.

"Saw your windows were dark last night," he said. "You folks have any heat?"

Mom admitted that we did not.

He nodded, as if that settled something. "I've got a gas stove and a fireplace. The Garzas and the Lees are already over. Bring the boy." He turned and walked carefully back across the ice before Mom could answer.

His living room was crowded and warm and smelled like pancakes. Mr. Abernathy stood at the stove, flipping pancakes with great seriousness. He did not say much, but he kept every plate full, and when Theo spilled syrup on the rug, he only shrugged and said, "Rugs wash."

The power came back on Friday afternoon. When we left, I thanked him, and he grunted, which I was beginning to understand was simply how he talked.

That spring, when my soccer ball rolled onto his lawn, I knocked on his door to ask for it instead of sneaking over to grab it. He handed it to me, and for the first time I could remember, he almost smiled.