Works

• JAWS 15.0.12085 with FF 33.1
• JAWS 15.0.12085 with IE 11.0.9600.17280
• JAWS 15.0.12085 with Chrome 39.0.2171.65
• NVDA 2014.3 with FF 33.1
• VO OS X 10.9.5 with Safari 7.0.6
• TalkBack with Android 4.4.2 with "Internet" 1.5.28
• TalkBack with Android 4.4.2 with Chrome 39.0.2171.59 (Doesn't support role="alert". Doesn't say "alert," but works due to explicitly setting aria-live.) (Same is true of non-hidden alerts.)
• NVDA 2014.1 with IE 11.0.9600.17280 (Doesn't support role="alert". Doesn't say "alert," but works due to explicitly setting aria-live.) (Same is true of non-hidden alerts.)
• iOS 8.1.1 VO Safari (just the first time)

Doesn't Work

• VO OS X 10.9.5 with Firefox 33.0.3 (But same is true of non-hidden alerts.)