"No." Vaughn sounded sullen, but otherwise under control, not likely to do anything too stupid immediately.

She sounded a little sullen, but dragons aren't very good at tone of voice.

Bob's command sounded sullen and hollow in the spaces of the corridor.

He sounded sullen, narrowing his eyes up at the Duke against the sun.

"Yes," Jaxom replied, and he sounded sullen even to himself.

"No," I said, and it sounded sullen even to me.

"You're not the only wolf in the hallway," Graham said, sounding sullen.

He heard his own voice and feared it sounded sullen.

"We could warn them," says Hunt, his voice so tired that it sounds almost sullen.

I knew I sounded sullen, but that was better than bursting into tears.