Amplify is an Awareness perk featured in Call of Duty: Ghosts. Players equipped with this perk will have enemies' footsteps amplified, as well has allowing the player to hear Dead Silence users, though they are slightly less audible than regular footsteps heard without Amplify, but still distinguishable. One note is that it only increases the footsteps' volume, not the range in which they can be heard.
It should be noted that crouching or going prone makes player movement almost completely silent, even without Dead Silence. This makes it dangerous to rely too much on Amplify itself, so it is advisable to also use other perks or pointstreaks that increase awareness of enemy movements.