the.com/echoes
Sound's stubborn refusal to die quietly, bouncing back to remind you it heard you.
means Repetitions of sound reflected off surfaces, or by extension any lingering trace of something past.
from From Greek Echo, a nymph cursed to repeat others' last words after love and the gods broke her — language's most poetic punishment.
Travel timeSound needs about a tenth of a second to register as separate.
Bat techBats and dolphins map worlds entirely by echo.
Memory senseEchoic memory holds sound for roughly four seconds.