I read a book on acoustics a long time ago that listed the properties of various woods, drywall, tile, insulation, and many more that I can't recall. Although I can't remember the name of the book I'm sure you could find something similar at your local library. That should give you the long answer to your question, if you want it.
The short answer, different materials have different acoustic properties, right? Glass has a tendency to reflect most direct sound.... depending on it's composition and thickness of course. Hard woods can be quite stiff and if done properly, can give a rich sound when used for an enclosure. Perhaps the maple shelf has the proper thickness and size to reinforce or resonate in a pleasing nature.
I hope I helped shed some light on what going on.....
Andrew
Synesthesia Studios
The short answer, different materials have different acoustic properties, right? Glass has a tendency to reflect most direct sound.... depending on it's composition and thickness of course. Hard woods can be quite stiff and if done properly, can give a rich sound when used for an enclosure. Perhaps the maple shelf has the proper thickness and size to reinforce or resonate in a pleasing nature.
I hope I helped shed some light on what going on.....
Andrew
Synesthesia Studios