Is there a way to test the Neural Engine without our Azure Services?

The Neural Voices need access the azure GPUs farms, so you can't run them locally like an embeded/edge scenario... If you use the Speech CLI, it is very easy to quickly try them out though. https://docs.microsoft.com/en-us/azure/cognitive-services/speech-service/get-started-speech-to-text?tabs=script%2Cbrowser%2Cwindowsinstall&pivots=programmer-tool-spx