next generation ;)
16 more cards could form the next deck for more diversity.
Most of the pictures should be well connected to some sound characteristics, also these kind of sounds should not be similar.
A few can be more suggestive of moods without clear sounds tied to them. Here are some of my ideas:
breaking cup, church-like building, fireworks, forest, snakes, water tap, whales
do you have anything more that is easy to draw and might sound unique?