How do I show 'emphasis' in the following Japanese sentence?

Solution 1:

I would suggest that you use the word do for emphasis in that case. Looking at TFD Online, we see that do is

2. Used as a means of emphasis: I do want to be sure.

You can put that emphasis in a couple of places.

Behind me comes a certain voice I do remember ...

or

Behind me does come a certain voice I remember ...

Of the two I prefer the first.

Reasoning: Since して is used to add emphasis and is an inflected form of する, and the bare verb form (する) has some pretty strong equivalence to the English auxiliary verb do, this feels like the best way to add emphasis without muddying the meaning of the original Japanese.