https://docs.microsoft.com/en-gb/azure/cognitive-services/speech-service/language-support https://docs.microsoft.com/en-us/dotnet/api/system.speech.synthesis.speechsynthesizer.rate?view=netframework-4.8&viewFallbackFrom=netcore-3.0
https://eu-west-2.console.aws.amazon.com/polly/home/SynthesizeSpeech