snasni lujvo

x1 is an (auditory) signal/alarm/notification/click/beep representing x2

Refers to an auditory symbol itself in an abstract sense. To refer to a specific instance of an auditory symbol at a given time and place, see snisna.

In notes:

klusni
x1 is a cultural symbol/icon/emblem/meme representing x2 (ka/si'o) to people x3 (loi/lo'e)
snisna
x1 is an alarm/beep/click/bell (sound) produced by x2