I had a sentence in Madness which read something like:
"The boat was tied to the dock as the tide came in."
/tied/ and /tide/ are not echoes, typographically or lexically, but they are absolutely echoes from an audible standpoint. Personally, I don't hear the words as I read, so I'll tend to slide right by that sort of thing, but many people do hear text in their heads. So it still counts.
Which thought in turn led me to remember a workshop story some years ago where the writer had said:
"The dog laid down to stand guard."
I pointed out you can't /lay down/ to /stand/ -- that the actions were directly contradictory. He didn't get it at first, because he was seeing the figurative meaning of /stand guard/. I finally asked him if he ever made puns. He said no he didn't. Punning is all about seeing the 'wrong' meaning in a word or phrase, and emphasizing it back to your audience. He saw the 'right' meaning of /stand guard/ and never noticed the conflict between the two action verbs embedded in his sentence.
That's not an echo, but it's rather similar. Of such nuances are good style made.