Echoes get fainter because each time the sound wave reflects off a surface, it loses some energy due to absorption, scattering, and dispersion. This energy loss causes the echo to decrease in intensity as it repeatedly bounces off surfaces and travels further away from the source.
fainter
fainter
The Echoes was created in 1959.
yes
I don't think we can answer that as we are seeing fainter and fainter stars as technologies improve. The Hubble Space telescope showed stars never seen before but I am sure there are even fainter ones that we might see with new technologies one day.
Echoes of Refuge was created in 2006.
Echoes of Honor was created in 1998.
Eternal Echoes was created in 2001.
Echoes from the Ocean was created in 1999.
Imperial Echoes was created in 1928.
Echoes of Eternity was created in 2005.
Echoes of an Era was created in 1981.