Ululation is the noun that goes with ululate: the long, high, wavering cry itself, or the act of making it. You can use it both ways. Uncountable, for the sound in general: "the air filled with ululation". Countable, for separate cries: "a single ululation rose from the back of the crowd", "their ululations carried across the valley". Like the verb, it belongs to writing rather than speech — news reports, novels, and writing about other cultures. A speaker at a bus stop would say "screaming" or "wailing". Because it names a sound rather than an emotion, it can go either way: the ululation at a funeral is grief, the ululation at a wedding is joy, and both are usually done by women together as something their culture expects, not as private feeling breaking out. It is also used for wind, sirens and animals — "the ululation of the wolves" — where it makes the sound feel eerie and drawn-out. If you are describing a sound and want the reader to hear it going up and down and lasting a long time, this is the word; if you just mean loud noise, it is too heavy.

（拉長聲的）哀號聲、顫音呼喊；婚喪場合那種高亢的顫音