diff --git a/googleapis/cloud/dialogflow/v2beta1/audio_config.pb.go b/googleapis/cloud/dialogflow/v2beta1/audio_config.pb.go
index c336115f0..0236e7752 100644
--- a/googleapis/cloud/dialogflow/v2beta1/audio_config.pb.go
+++ b/googleapis/cloud/dialogflow/v2beta1/audio_config.pb.go
@@ -14,7 +14,7 @@
 
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
-// 	protoc-gen-go v1.25.0
+// 	protoc-gen-go v1.25.0-devel
 // 	protoc        v3.13.0
 // source: google/cloud/dialogflow/v2beta1/audio_config.proto
 
@@ -794,6 +794,9 @@ type VoiceSelectionParams struct {
 	// Optional. The name of the voice. If not set, the service will choose a
 	// voice based on the other parameters such as language_code and
 	// [ssml_gender][google.cloud.dialogflow.v2beta1.VoiceSelectionParams.ssml_gender].
+	//
+	// For the list of available voices, please refer to [Supported voices and
+	// languages](https://cloud.google.com/text-to-speech/docs/voices).
 	Name string `protobuf:"bytes,1,opt,name=name,proto3" json:"name,omitempty"`
 	// Optional. The preferred gender of the voice. If not set, the service will
 	// choose a voice based on the other parameters such as language_code and
diff --git a/regen.txt b/regen.txt
index de22faea7..5739ae458 100644
--- a/regen.txt
+++ b/regen.txt
@@ -1 +1 @@
-9ecdacc9a00e1dd443b11bf10215d6e7648db8a7
\ No newline at end of file
+039f113828fc599a8da3b23d056ba2812d3d211d
\ No newline at end of file