How do I modify speech contexts in Dialogflow fulfillment - google-app-engine

Question

An issue I am seeing is that when I ask in dialogflow for the user to spell out their user id like joesmith2014, there are a large number of errors. The follow post suggested that I can fix this by using speech context to tell the speech to text engine that the user will be spelling out alphanumerics.
https://stackoverflow.com/questions/62048288/dialogflow-regex-alphanumeric-speech
I can't figure out how you would do this while using the actions-on-google library or can this not be down in the fulfillment webhook?
Thanks.

Answer 1

As an example, I created an agent called “alphanumeric” because it will accept any alphanumeric value I send following the next steps:
Check the box regexp entity
Add a single entry, ^[a-zA-Z0-9]{3}[a-zA-Z0-9]*$
Then save it
Your agent should look something like this:
Please note that the regexp entity I added is strict in that it is looking only for a string of alphanumerics, without any spaces or dashes. This is important for two reasons:
This regexp follows the auto speech adaptation requirements for enabling the "spelled-out sequence" recognizer mode.
By not looking for spaces and only looking for entire phrases (^...$), you allow end-users to easily exit the sequence recognition. For example, when you prompt "what's your order number" and an end-user replies "no I want to place an order", the regexp will reject and Dialogflow will know to look for another intent that might match that phrase.
If you are only interested in numeric values, you can create a more tailored entity like [0-9]{3}[0-9]*, or even just use the built-in #sys.number-sequence entity.

Answer 2

Dialogflow ES fulfillment cannot affect speech recognition quality because speech-to-text processing happens before the Dilaogflow request is sent to Dialogflow fulfillment. Check the diagram in the Dialogflow ES Basics documentation.
You can improve speech recognition quality either by enabling auto speech adaptation in the agent settings or by sending speech contexts in the Dialogflow API requests. Note that speech contexts sent via API override implicit speech context hints generated by auto speech adaptation.
If you use regexp entities, make sure that your agent design meets all the requirements listed in this speech adaptation with regexp entities document. See an example of how an intent that collects the employee ID and satisfies these requirements may look like:
When testing the agent, make sure that you test it consistently via voice, including the inputs preceding the utterance expected to match a regexp entity.
This tutorial for iterative confirmation of spoken sequences may also help with the agent design.