Sentence:  When he was asked a question or addressed in such a way that some response was inescapable , he would answer ; if , as often happened , he had to repeat because he had spoken too softly , he would repeat his words in the same way , without emphasis or <WSD>impatience</WSD> , only a little louder . 
Meaning of the word marked with <WSD> tags:  a lack of patience; irritation with anything that causes delay