He did sound drowsy.

"I am happy if you are happy," she said, sounding drowsy.

'Can't seem to stay awake,' she said, though she didn't sound drowsy.

Her voice sounded drowsy, like a sleepwalker's.

Within minutes their voices sounded drowsy, and at last the one sentry stood up, stretched and yawned.

Her voice already sounded drowsy and on the edge of sleep.

"There were books on the desk," she said, beginning to sound drowsy.

Brianna sounded pleasantly drowsy as well.

"No," I said, trying to sound equally drowsy.

Poirot sounded rather drowsy as he asked, "Why are you telling me all this?"