Dialogflow voice agents use Speech-to-Text for speech recognition, which is included in Dialogflow pricing . Dialogflow automatically selects a speech recognition model for you, but you can optionally specify the model.
Available models
All available models are listed at Speech-to-Text models . Select a model that is best suited to your domain and supports your agent language and speech features .
If a model is not explicitly specified , then Dialogflow auto-selects a model based on the audio configuration in API requests and agent settings.
The following models typically have the best performance:
- telephony_short (best for telephony Dialogflow)
- telephony (best for Agent Assist) (also good for telephony Dialogflow when advanced timeout-based end of speech sensitivity is enabled)
- phone_call (good for Agent Assist and telephony Dialogflow)
- latest_short (best for non-telephony Dialogflow)
- command_and_search (best for languages where other models are not available)
Specify a model
You can supply the model for an agent, flow, or page with the model selection setting .You can also supply the model when calling the Sessions.detectIntent 
or Sessions.streamingDetectIntent 
methods;  
Select a protocol and version for the Session reference:
| Protocol | V3 | V3beta1 | 
|---|---|---|
|   
REST | Session resource | Session resource | 
|   
RPC | Session interface | Session interface | 
|   
C++ | SessionsClient | Not available | 
|   
C# | SessionsClient | Not available | 
|   
Go | SessionsClient | Not available | 
|   
Java | SessionsClient | SessionsClient | 
|   
Node.js | SessionsClient | SessionsClient | 
|   
PHP | Not available | Not available | 
|   
Python | SessionsClient | SessionsClient | 
|   
Ruby | Not available | Not available | 
ConversationProfile 
 
for Agent Assist 
.
Specifying the model in a detect intent or conversation profile API call will
override any model selections applied to the agent, flow, or page, unless you
enable the  Override request-level speech
model 
setting.  

