https://uxplanet.org/understanding-speech-recognition-to-design-better-voice-interfaces-bef36b8614f

One key component of a Voice user interfaces(VUI) is automated speech recognition (ASR) that enables users’ speech to be translated into text. There are a number of free and paid services available that provide ASR engines. When choosing an engine, it is important to keep in mind the following two things:

Again, not all ASR tools will have advanced features like N-best lists, end of speech timeouts or the ability to incorporate custom vocabularies. It might be quicker to start with the cheapest ASR tool, however if the recognition accuracy is sub-standard, or the endpoint detection does not work very well, it is going to frustrate your users to eventually give up on the product.