As of this writing, Amazon has thousands of sources for flash briefings.  The sources they include can be hyper-local like your local news station. Amazon also has specific topics like tech or business, or general info.  Many of these sources, like NPR, are podcasts provided by Tune-In.  These briefings are audio files Alexa plays for you.  Other sources like the AP news stories are read in Alexa’s voice.  I wish Amazon told you which ones were audio files because her voice drones on after a while.  I hope I get to change her voice like I can with Siri.  Right now, you can just change the language to the English (UK) or German.
Note: Your Flash Briefing settings apply to all Alexa devices registered to your Amazon account, and all users in your home get access to the same Flash Briefing content. However, if you or anyone in your home has a voice profile, Flash Briefing automatically skips stories and news items you've already heard. To learn more, go to About Alexa Voice Profiles.
Amazon's Alexa is the voice-activated, interactive AI bot, or personal assistant, that lets people speak with their Amazon Echo, Echo Dot and other Amazon smart home devices. Like Siri and Cortana, Alexa is designed to respond to a number of different commands and even converse with users. Alexa comes with more than a few capabilities: playing music, pulling up the weather or even reading news. But Alexa Skills are apps that give Alexa even more abilities, letting her speak to more devices even websites.

Alexa, open Save Water by Colgate. With this skill, Alexa begins a dialogue where users can receive water conservation facts and tips while brushing their teeth. To encourage tooth-scrubbing listeners to turn off the sink faucet while they brush, Alexa will even play the sound of running water to replace the sound of actual water coming out of the faucet. 
If you think you’d like a briefing in the future, but not now, just toggle it off. If you want to permanently disable a Flash Briefing skill, you’ll need to head over to the Skills section in the app and then tap Your Skills.  Find the skill you want to disable and then tap Disable Skill. You don’t delete the skill, which makes sense since nothing installs on your Alexa device.
Like all AI devices that use National Language Processing or NLP, Alexa does not understand all voices easily. But she learns to understand her people over time. She does, however, require people to speak in simple terms, with appropriate pauses, and use specific word orders. There are many times when she will say "I'm sorry, I don't know the answer to that question." More than likely, she doesn't recognize a word order or misunderstood the question.
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