Speaker Strobes and other devices -- scratchy noise?!

Something weird I’ve seen over the past few days is this scratchy-raspy sorta noise on speaker strobes and loudspeakers. If you listen to the alarms in the video below, you’ll likely hear what I’m talking about. The reason I ask this is that the bell at my new school makes this raspy noise too, just a 440hz tone instead of 520hz. Anyone know what that is or what it means? Just curious…

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possibly a bad chip or capacitor.

Maybe whoever made the tone designed it that way. It is more distinct

the ones at school do it too thre loudspeakers do