Have you ever tried placing echoes in a poem? I am not talking about a form like the villanelle, where the first and third lines of the first stanza, which is a tercet (3 lines), are repeated at set intervals and come together as a rhyming couplet at the end of the final stanza which is a quatrain.
If you start a poem with the words ‘I hear’ or ‘I saw’ and use either of these to start each stanza, it will not only be creating an echo but will bring a theme to mind. It might be something from memory, or possibly something you just heard or saw.
Different ways to use echoes can be through similar sounding words For instance, try the assonantal and consonantal sounds in words like lash/wash or pattern/ fatter. Such similar sounds in words create not only echoes but slight rhymes.