Question

What I want to do is create an API that translates human speech into the IPA (International Phonetic Alphabet) format. My question is, where are the resources on how to decode speech at the level of the original audio waveform. I looked for an API, but most of what I found just translates straight to the roman alphabet. I’m looking to create something a little more accurate in its ability to distinguish vocal phonetics.

Answer 1

I would just like to start out by saying that this project is much more difficult and complicated than you think it is. Speech to text processing is a very large and complicated field with a huge amount of research that has been done into it. The reason most parsers send things straight to roman characters is because most of their processing is a probabilistic matching of vague sounds with their context of other vague sounds to guess which words make sense together. You are much more likely to find something that will give you Soundex rather than IPA. That said, this is a problem that has been approached on several fronts. Your best bet is probably the Sphinx project from CMU.

http://cmusphinx.sourceforge.net/wiki/start

That will give you a good start, but you make an assumption that speech to text processing is a lot more developed than it actually is, and there is no simple way of translating speech to IPA through the waveform with any kind of accuracy. Sphinx is very modular and completely open source and so it would give you a huge amount of power at your fingertips, and at that point whether or not you can figure out how to make this work is up to you, but again. This is not a solved problem in any way.