Reply #2: We have 65 sirens blaring...with a voice...evey Tuesday at noon...

[Dunvegan]

...that can be heard throughout the heart of the city of San Francisco.

First there is the rising wail of the siren.

Then as it reaches crescendo, it cuts out and there is a booming male voice, far louder any and all city sounds:

"This is a test of the outdoor warning system. This is only a test."

The first time it was tested, although trained in first response, it made me stop and wonder...somewhat discomfited.

About San Francisco's Sirens: http://abclocal.go.com/kgo/story?section=i_team&id=3627030

Edited to say: The city's only ordered one chip, that one voice and one test message. No chips or recordings for any emergency. If there was an emergency today, I suppose they'd switch on the sirens and "the voice" would tell us "This is only a test."

From the ABC 7 San Francisco article linked above:

Patrick Crawford: "That's a concern, having a system that has all the features turned on would be an important thing."

The city has been busy just trying to get the basic siren to work. They didn't want one of those cold, new high-tech tones.

Someone in the local government decided it would be a good idea to use the air raid siren sound from the old system. So they carted off one of the horns to ATI in Boston. Engineers recorded the sound, tweaked it, and installed it on the new system. That's what Gavin Newsom unveiled one year ago this week.

The problem is the fluctuation of the sound is blowing out the speakers. The city's had to replace more than 350 drivers - the sound-producing mechanism inside the sirens. We broke that news to Michela Alioto-Pier, supervisor for the Marina District that was especially hard hit by Loma Prieta.