Surge. A triangle wave at 220 Hz, originating from Subway Tunnel. Recorded in a open air environment, era: 1970s. One of 5555 echoes — sounds no one thought to save.
Name
ECHO #1659 — Surge
ID#1659
Rarity
LO:53%
Frequency
220 Hz
X-HI:8%
Wave Type
Triangle
X-HI:8%
Resonance
Warm
X-HI:11%
Era
1970s
X-HI:6%
Origin
Subway Tunnel