I get to read about things like this -
https://en.wikipedia.org/wiki/%22Heroes%22_(David_Bowie_song)#Inspiration_and_recording
"Bowie's vocal was recorded with a "multi-latch" system devised by Visconti that creatively misused 
gating.
[20]
 Three microphones were used to capture the vocal, with one microphone 
nine inches from Bowie, one 20 feet away and one 50 feet away. Each 
microphone was muted as the next one was triggered. As the music built, 
Bowie was forced to sing at increased volumes to overcome the gating 
effect, leading to an increasingly impassioned vocal performance as the 
song progresses.
[19]
 Jay Hodgson writes, "Bowie's performance thus grows in intensity 
precisely as ever more ambience infuses his delivery until, by the final
 verse, he has to shout just to be heard....The more Bowie shouts just 
to be heard, in fact, the further back in the mix Visconti's multi-latch
 system pushes his vocal tracks, creating a stark metaphor for the 
situation of Bowie's doomed lovers".
[21]"