Oh! That's a bit fo a surprise. I guess the refelcted sound waves end up crashing into one another and cancelling out...?
It's cool that you got to expereince those things. Chant...makes one wonder about whether/the degree to which it all (music and the arrangement of interior space) developed in tendem, each influencing the other? Could the space have been influenced at all by a desire to achieve the effect you described...?