Microsoft has some amazing TTS technology. https://azure.microsoft.com/en-us/products/cognitive-services/text-to-speech/ https://azure.microsoft.com/en-us/produ

Microsoft has some amazing TTS technology. https://azure.microsoft.com/en-us/products/cognitive-services/text-to-speech/ https://azure.microsoft.com/en-us/products/cognitive-service... I know it is not Firefox, but Edge has it built-in and it works great! Highly recommended to try.