Word for when something makes something else seems smaller in a relative manner

Solution 1:

Based on the title of the question (which uses the word "smaller") I would have suggested dwarf:

dwarf (verb): Cause to seem small or insignificant in comparison. (from [https://www.merriam-webster.com/dictionary/dwarf])1.

While I have, on occasion, read about a "big" and maybe even a "small" voice, those wouldn't be my first choice of words. I'm more used to hearing voice described as "loud" or "soft." In that sense I don't like my own answer. I'm submitting it anyway since the question is specifically looking for words about relative size (rather than relative loudness).

Solution 2:

The general question is answered by the metaphorical sense of eclipse.

eclipse verb (IMPORTANCE) [ T often passive ]

...

(2) to make another person or thing seem much less important, good, or famous:

• The economy has eclipsed all other issues during this election campaign.

[Cambridge English Dictionary]

For sounds, it is not a particularly good metaphor.

You'd probably use drown/ed out.

drown out Verb [[multi-word] [transitive]] (idiomatic)

To cover, obscure, or hide by being louder than.

• He uses the music to drown out other noises around him.

[Your Dictionary]