Both Uses of

recede
in
Angelfall

The buzz of the party breaks into bits of conversation as a couple of men approach the bathroom, then recede into background noise as they leave the area.†
p. 202.8

recede = to move away or diminish (become less)

But I take it as a sign that the pain from the stinger must be receding if there's room for me to feel other sensations like smoke irritation.†
p. 272.0 *

receding = moving away or diminishing (become less)

Definition:

to move away or diminish (become less)

The exact meaning of recede depends upon its context. For example:

"We can't move back in until the floodwaters recede." -- diminish and move away
"Her fear receded." -- diminished
"The waves first advance and then recede." -- move away
"The news story receded into the background as it was replaced by new stories." -- received diminished attention
"a receding hairline" -- diminished hair (each year the line where hair stops growing is higher on the forehead)
"She has a receding chin." -- sloping back (as contrasted to sticking out)