diff --git a/adapter/volcano/request.go b/adapter/volcano/request.go
index a244263..b2fd932 100644
--- a/adapter/volcano/request.go
+++ b/adapter/volcano/request.go
@@ -51,7 +51,7 @@ func buildRequest(opts Options) ([]byte, error) {
 
 	body := requestBody{
 		User:      ttsUser{UID: opts.UID},
-		Namespace: "BidirectionalTTS",
+		Namespace: "UnidirectionalTTS",
 		ReqParams: ttsReqParams{
 			Text:    opts.Text,
 			Speaker: opts.Speaker,