diff --git a/src/audio/interfaces.ts b/src/audio/interfaces.ts
index 288bd2b..06612ff 100644
--- a/src/audio/interfaces.ts
+++ b/src/audio/interfaces.ts
@@ -31,6 +31,8 @@ export interface SpeechToTextResponse extends BaseResponse {
     timestamp: number[];
     text: string;
   }>;
+  language_detected?: string; // only available if language is auto
+  confidence?: number; // only available if language is auto
 }
 
 export interface SpeechToTextWebhookResponse extends BaseResponse {