Why the alert sounds deliberately harsh
The sound is made by playing two steady tones at once: one vibrates 853 times per second, the other 960 times per second. Each tone alone would sound smooth and plain. Together, they clash because their pitches do not fit into the simple whole-number relationships that make many musical intervals sound settled. The result is a tense, rough-edged buzz that stands out from ordinary speech and programming.
A signal built to cut through
The frequencies sit in a range that small speakers can reproduce, and the paired tones create a recognizable sound rather than a voice that could be mistaken for part of a broadcast. In the U.S. Emergency Alert System, the attention signal is part of the broadcast warning; separate coded information is used by the system to identify and relay alerts.
That separation matters: the tones are meant for people to hear, while the codes help alert equipment handle the message. The discord is not decoration. It makes the warning difficult to ignore precisely because it sounds unlike the calm, familiar patterns around it.
