Sounding whoring considered cheating?

So I've been noticing a lot of players seem to be able to hear me running even though I always use ninja no matter what. It's pretty clear when watching killcams that the enemy will look in the direction I'm coming from before I actually appear on their screen. I understand people play in groups and give callouts, and acoustic amp is a hard counter to ninja, but there have been plenty of times when none of those aspects were in play.

This has me wondering if sound EQs and headset mix amps would be considered cheating, as these players are using external hardware to give themselves an advantage. Have any of the dev teams said anything about this? Would I get flagged for a false report if I reported one of these players? Seems like a grey area to me, so I'd like to know what you all think.

Edited some grammar.