teller
n
1 person who receives and paysout money in a bank (银行的)出纳员.
2 person appointedto count votes, eg in the House of Commons (投票时的)计票员(如下议院中者).
3 (esp in compounds 尤用以构成复合词) person who tells stories, etc 讲故事等的人; 讲述者
a story-teller 讲故事的人
a marvellous teller of jokes 笑话讲得很精彩的人.
I suggest that we ask users of this machine what they think about it. We can photograph them using it too. Then we can put their comments at the top of the advertisement in big print. We can bring in some humour too. People enjoy reading humorous ads.