I haven't seen this mentioned at all, and it hasn't been fixed in a long time.
The proximity bomb, and the proximity C4 are broken.
after the initial beep, (which attracts attention via sound) it continues to attract nearby npcs via sound although it shouldn't do that after the initial beep.
I tested it multiple times, if you plant a proximity bomb, (or c4) and nobody hears it at first, but eventually when someone walks by, even if they are not possibliy seeing it, they'll go "huh" and act as if they heard a sound and go directly to the proximity mine.
This defeats the entire purpose of proximity bomb and proximity c4, which in my opinion are some really fun gears.
Please fix if possible soon
P.S. This is on PS4