There was a guy who had trapazoidal violins made and had people judge their quality against standard violins of good quality. It covered the gamut from non-musical people to music lovers to producers to musicians. What they found was that it was a crap-shoot. There was no telling who was going to prefer which violin sound which proves the shape really has nothing to do with the sound. What they did discover, though, was that trapazoidal violins didn't last very long compared to standard violins.