Echo-y Tunnels and Stairwells

Some aspects of sound and acoustics fascinate me. Every time I walk through a tunnel or in another enclosed space made of brick or cement, I have a desire to sing something like Gregorian chant or the dwarf song from the first Hobbit movie or something similar. This evening the a cappella group I direct went to a stairwell to sing a couple of songs, and the sound was wonderful! I am so grateful for the acoustics of tunnels and stairwells. That five-second-or-more reverberation is magnificent.