The hidden message on my Taiwanese cover

Here's something cool. My mom informs me that there's a hidden pun on the traditional Chinese cover (available in Taiwan, Hong Kong, etc.)

Look carefully at characters at top right and bottom left--see how the bottom half of each is shaded out, almost ghostly? At top right, the radical for "ear" (耳) is shaded out; at bottom left, the radical for "mouth" (口) is shaded out. A nod to how no one in this family speaks (or listens)...

I really love this cover, but love it even more now that I know this.