speechenablement.md: Update text related to Azure regions (#1904)

* speechenablement.md: Update text related to Azure regions

* speechenablement.md: Update text related to Azure regions

* Fix typo

Author: dargilco

docs/howto/assistant/csharp/speechenablement.md

@@ -40,8 +40,8 @@ Create a simple application that enables you to speak to your newly created Virt
 
 The first step is to create a Microsoft Speech instance to perform the Speech-To-Text and Text-To-Speech capabilities for your assistant.
 
-- Create a Microsoft Speech Cognitive Service instance in your Azure Subscription using the [Azure Portal](https://ms.portal.azure.com/#create/Microsoft.CognitiveServicesSpeechServices)
-- At this time the Direct Line Speech Channel is currently [only available](https://docs.microsoft.com/en-us/azure/bot-service/bot-service-channel-connect-directlinespeech?view=azure-bot-service-4.0#known-issues) in `westus2` so we recommend you use this region to reduce latency.
+- Select an Azure region. Direct Line Speech Channel is a preview service limited to [these Azure regions](https://docs.microsoft.com/en-us/azure/cognitive-services/speech-service/regions#voice-first-virtual-assistants). For best performance (reduced round-trip time) deploy your Virtual Assistant bot and Direct Line Speech channel to the same Azure region, and one that is closest to you. To help you decide, look up exact [geographical location](https://azure.microsoft.com/en-us/global-infrastructure/locations/) for each Azure region.
+- Create a Microsoft Speech Cognitive Service instance in your Azure Subscription using the [Azure Portal](https://ms.portal.azure.com/#create/Microsoft.CognitiveServicesSpeechServices). In the *Location* field specify the selected Azure region based on the above.
 - Once created, retrieve one of the speech **subscription keys** and store this ready for later in this tutorial. 
 
 ## Add the Speech Channel to your Assistant
@@ -78,7 +78,9 @@ private const string speechSubscriptionKey = "YourSpeechSubscriptionKey";
 
 ## Changing the Voice
 
-Now let's change the default voice (`Jessa24kRUS`) configured within your Virtual Assistant to a higher quality [Neural voice](https://azure.microsoft.com/en-us/blog/microsoft-s-new-neural-text-to-speech-service-helps-machines-speak-like-people/).
+Now let's change the default voice (`Jessa24kRUS`) configured within your Virtual Assistant to a higher quality [Neural voice](https://azure.microsoft.com/en-us/blog/microsoft-s-new-neural-text-to-speech-service-helps-machines-speak-like-people/). Note that Neural voices will only work with speech subscription keys created for certain locations (regions). See the last column in the [Standard and neural voices](https://docs.microsoft.com/en-us/azure/cognitive-services/speech-service/regions#standard-and-neural-voices) table for region availability. If your bot is configured for Neural voice and your speech subscription key is for a region not enabled for Neural voices, Direct Line Speech channel will terminate the connection with the client with an Internal Server Error (code 500). 
+
+To switch to Neural voice: 
 
 1. Open your Assistant Solution in Visual Studio.
 2. Open `DefaultWebSocketAdapter.cs` located within your `Adapters` folder.