Hollow. A sine wave at 20 Hz, originating from Nuclear Plant. Recorded in a underwater environment, era: 1970s. One of 5555 echoes — sounds no one thought to save.
Name
ECHO #4419 — Hollow
ID#4419
Rarity
HI:17%
Frequency
20 Hz
EX:4%
Wave Type
Sine
X-HI:13%
Resonance
Warm
X-HI:11%
Era
1970s
X-HI:6%
Origin
Nuclear Plant