Most simple way without running anything else, see VoiceMonkey.io. Need to do things in multiple places but fairly easy once you understand it.
You'll create a device there, then link voicemonkey to your Alexa account, add the device to Alexa in the app, then in BI under Alerts > Actions > On alert you'll add a line for a web request that looks something like this:
api-use.voicemonkey.io/trigger?access_token=your_access_token&secret_token=your_secret_token&monkey=your_device_name&announcement=Hello%20monkey