When we use speech recognition systems, there are several components that are working together. Two of the more important components are acoustic and language models. The first one labels short fragments of audio into sound units. The second helps the system decide the words, based on the likelihood of a given word appearing in certain sequences.

Although Microsoft has done a great job of creating comprehensive acoustic and language models, there may still be times when you need to customize these models.

Imagine that you have an application that is supposed to be used in a factory environment. Using speech recognition will require acoustic training of that environment so that the recognition can separate it from usual factory noises.

Another example is if your application is used by a specific group of people, say, an application for search, where programming is the main topic. You would typically use words such as object-oriented, dot net, or debugging. This...