I love the word "ululation" because of its onomatopoetic nature and the joyous sound it represents. Anyone who has been to a Middle Eastern or African celebration can't help but smile at the high-pitched "lalalalalala" that greets the participants. It is a sound that comes from deep within the throat and deep within the heart.
I have always thought that the root from which this Hebrew word comes is related to ululation. Take away the prefix ("y'") and the suffix ("kha") and what remains is "Hal'lu." And that word, from the root heh-lamed-lamed, is very familiar to us – it is part of the exclamation "hallelujah," meaning "praise God."
The root "h-l-l" means to ascribe praise or light. When it appears in another familiar form, "Hallel," it refers to the Psalms of praise that are collected in the prayer book for recitation on holidays and other special occasions, and included as one of the steps in the Passover seder. With slightly different vocalization (vowels), it is easy to connect the great sage Hillel with the notion of someone who shed a tremendous amount of light on the texts of Torah. The meaning of "y'hal'lukha" is pretty easy to understand – "they will ascribe You [God] praise and light."
But here is an instance in which the meaning, however appropriate and elevating, is less meaningful than the interpretation. I have heard "hallelujah" sung and shouted, proclaimed, pronounced, parsed, and proposed as a question, but at its most powerful is the reverberating sound it recalls, not just the ululations of joyful celebrants but also, as Psalm 150 recalls, the sounds of drums and lyres and trumpets and horns and, ultimately, every living breath that gives praise to God.
If we can hear that excitement in every recitation of this word, we will have within us the essence of prayer.