She does not need to speak, the art will do it for her, but unlike the expressive purpose of museum artwork, the point of this expression is to reinforce a relationship rather than speak to strangers. There is a public, shaming potential to the pot lid's use such as using the lid when her husband is having company. Context can add to the meaning of the lid, but still, there is some control over who hears the message, unlike the message conveyed by art to a person strolling through a museum, whose presence does not usually add or subtract from the meaning of the work of art.

Art is not done by professionals in this West African tribal context, rather everyone has the potential to make art, or to read art, in fact it is necessary in this case, that the husband be fluent in the language of the pot lids and other symbolic exchanges pertaining to marriage. The images of the pot lid also...

Some parallels in Western culture might be a wife deliberately burning her husband's dinner, or refusing to serve his favorite meal, but these would be purely personal exchanges between the two people, and would not be understood by a visitor, as is the language of the pot lids. The power of this method of communication is that it is indirect, yet clearly understood, and it uses art to convey intense feeling, but in a way that everyone within the community can immediately understand, not just the married couple.
Works Cited

Woyo people,

Congo (Zaire) pot lid." The Stanley Collection:

The University of Iowa Museum of Art. January 1999. 25 Mar 2007. http://www.uiowa.edu/~africart/toc/chapters/kml/KMD1.html