Now on to the sound; this is the first alarm clock I have ever purchased that wakes me (and the rest of the neighborhood) up 100% of the time. I work full time on an ambulance, and honestly, I can’t decide what’s louder, my siren or this alarm clock! The very first time I used it, my neighbor came knocking on my door because it also woke him up.

https://www.amazon.com/Sonic-Alert-SBB500SS-Extra-Loud-Flashing/dp/B000OOWZUK