How make this in a space of 7.5m length x 2.5m breadth?
I like wood, (glue laminated beams), except the use calls for some good reverberations.
Wood absorbs sounds rather than reflects them....unless you covered the interior with plaster.
A metal roof would not be appropriate, because it would need insulation on the interior to protect it from condensation...which would defeat the acoustics you’re probably searching for...
Btw, I’d think there would be two “zones” (the apex of each curve) that would be especially intriguing to stand in because of the sound.
Side note: Are you going to orient the space in a North-South direction with the clerestory facing East? That way the early morning light could penetrate deep into the space through the clerestory windows? I think it would be nice to see “the light” move across the ceiling of the upper arch. (Where can I go to see this when it’s completed?)