After syncing Watson Speech to Text, you may notice that a Custom Words dropdown becomes visible in the inspector:

Any word in your lexicon that is not a part of the base language model will be added as a custom word (also known as an out-of-vocabulary word). This is one of the powerful things about using custom language models, that these words will now be correctly recognized. It’s also a useful way to notice typographical errors in your intents or entities. If a custom word shows up with a typo you can find and fix the typo.

In the Custom Words list in the Inspector you can change the display as and pronunciations for each custom word. Display As defines how the word should appear in the speech to text transcript. For example, we may want “mixspace” to show up as “Mixspace”. The Pronunciations is a comma delimited list of accepted pronunciations for the custom word. After changing any of these settings you can click the Sync Watson Speech to Text button to submit the changes.

See the Watson documentation for more information.