Still. A square wave at 220 Hz, originating from Subway Tunnel. Recorded in a cave environment, era: 1970s. One of 5555 echoes — sounds no one thought to save.
Name
ECHO #5424 — Still
ID#5424
Rarity
LO:56%
Frequency
220 Hz
X-HI:8%
Wave Type
Square
X-HI:10%
Resonance
Harsh
X-HI:8%
Era
1970s
X-HI:6%
Origin
Subway Tunnel