Music has been existence since virtually the beginning of time, both in the animal and the human world. Music is enjoyed by both individuals and groups, and it can be experienced both as a participant and as a listener. Music can be used as a basis for communication (as in the "clicking" languages) and as a form of expression. Sometimes music is simply for pleasure and fun. Virtually everyone in the world knows music, in some form, almost from birth. Any of these descriptions could be incorporated, wholly or in part, into a title.
Your essay, however, is more specific. It is focused on music and its ability to affect or change mood. This also has a long history: from the biblical David who soothed King Saul by playing the lyre when Saul was afflicted with a troubled spirit (I Samuel 16:23) to the snake-charmers of India who calm rattlesnakes bent on attack. I am certain you have even better and more contrasting examples in your essay, so (using my two examples) perhaps something like "From King to Snake: The Power of Music to Effect a Change of Mood."
Another idea is to take a bit of a particularly apt quotation you will be using in your paper to serve as a kind of "teaser" for what is ahead. This would only work with a short phrase or couple of words, but it would be an effective way to tie your title to your paper.
You might also take a quote about music, of which there are many, and make a reference to them. For example, arguably the most famous quote about music is this one:
Musick has Charms to sooth a savage Breast,
To soften Rocks, or bend a knotted Oak.
It was written in 1697 by William Congreve in his poem The Mourning Bride. Some ideas from this quote include referencing the lesser-quoted second line to introduce the subject:
- Music: The Power to Soften Rocks or Bend Trees
- Softening Rocks and Bending Knotted Oaks: The Power of Music to Move
- Even the Rocks and the Trees Hear and are Moved by Music
Another idea is a play on words. In that case, the first line of the poem might be more effective. In fact, most people think the saying includes the word "beast" instead or "breast," this might make for an interesting play on words:
- "Beast" or "Breast," Music Has the Power
This idea would work with any relatively recognizable quote which you are using in your essay.
Another idea is to write something alliterative, as you already have the two "M" words: music and mood. It is not a far stretch to think about other key "M" words you could use: make, move, motivate, and even "eMotion."
You also have all kinds of potentially interesting ideas when you think about musical terms (such as melody) and emotion terms (such as passion).
Finally, you always have your own words, as written in the essay, which can serve as an interesting title if it serves to intrigue your readers.
Of course, every title has to serve two purposes, and they are the first considerations for anything you choose. First, a title should provide an accurate representation of what is contained in your essay. Second, the title should capture the attention of your readers. Other considerations include tone, formality, and requirements.
The tone of the title should generally match the tone of the essay, though of course it can be a bit more light-hearted than a researched writing. Your professor may prefer at least something didactic (informative) in the title, so be sure to do that, even if you choose something more "catchy." Also consider any requirements for the assignment.