I say, trying to sound sceptical.

I hope I don't sound sceptical.

No you don't sound sceptical.

Berrocal couldn't help sounding a little sceptical.

But I begin to sound sceptical.

The man sounded sceptical.

Her voice sounded sceptical.

Initially she sounded sceptical, and then neutral, and then somewhat convinced.

He tried to keep his tone level, not wishing to sound too sceptical.

I tried to sound sceptical.