There are a variety of phrases that can be used in place of "sound an alarm." Some options include "raise the alarm," "notify authorities," "alert the public," "broadcast warnings," or "announce an emergency." These phrases all convey the same urgency and seriousness as "sound an alarm," while offering slight variations in tone and implication. "Raise the alarm," for example, sounds slightly more urgent, while "notify authorities" implies a specific action. "Alert the public" suggests a broad dissemination of information, while "announce an emergency" feels slightly more formal. By varying the wording around the idea of sounding an alarm, speakers and writers can create more nuanced tone and meaning.