Murmur. A triangle wave at 741 Hz, originating from Subway Tunnel. Recorded in a anechoic environment, era: 2010s. One of 5555 echoes — sounds no one thought to save.
Name
ECHO #1083 — Murmur
ID#1083
Rarity
MID:49%
Frequency
741 Hz
X-HI:5%
Wave Type
Triangle
X-HI:8%
Resonance
Hollow
X-HI:5%
Era
2010s
X-HI:7%
Origin
Subway Tunnel