diff --git a/src/backends/speech_dispatcher.rs b/src/backends/speech_dispatcher.rs
index 009a8fb..89ab24c 100644
--- a/src/backends/speech_dispatcher.rs
+++ b/src/backends/speech_dispatcher.rs
@@ -149,6 +149,18 @@ impl Backend for SpeechDispatcher {
         let is_speaking = speaking.get(&self.0.client_id()).unwrap();
         Ok(*is_speaking)
     }
+
+    fn voice(&self) -> Result<String,Error> {
+        unimplemented!()
+    }
+
+    fn list_voices(&self) -> Vec<String> {
+        unimplemented!()
+    }
+
+    fn set_voice(&mut self, voice: &str) -> Result<(),Error> {
+        unimplemented!()
+    }
 }
 
 impl Drop for SpeechDispatcher {
diff --git a/src/backends/tolk.rs b/src/backends/tolk.rs
index 370da65..e6d0f07 100644
--- a/src/backends/tolk.rs
+++ b/src/backends/tolk.rs
@@ -101,4 +101,16 @@ impl Backend for Tolk {
     fn is_speaking(&self) -> Result<bool, Error> {
         unimplemented!()
     }
+
+    fn voice(&self) -> Result<String,Error> {
+        unimplemented!()
+    }
+
+    fn list_voices(&self) -> Vec<String> {
+        unimplemented!()
+    }
+
+    fn set_voice(&mut self, voice: &str) -> Result<(),Error> {
+        unimplemented!()
+    }
 }
diff --git a/src/backends/web.rs b/src/backends/web.rs
index 664793c..a8be3c2 100644
--- a/src/backends/web.rs
+++ b/src/backends/web.rs
@@ -131,4 +131,16 @@ impl Backend for Web {
             Err(Error::NoneError)
         }
     }
+
+    fn voice(&self) -> Result<String,Error> {
+        unimplemented!()
+    }
+
+    fn list_voices(&self) -> Vec<String> {
+        unimplemented!()
+    }
+
+    fn set_voice(&mut self, voice: &str) -> Result<(),Error> {
+        unimplemented!()
+    }
 }
diff --git a/src/backends/winrt.rs b/src/backends/winrt.rs
index 7464f58..2e8af98 100644
--- a/src/backends/winrt.rs
+++ b/src/backends/winrt.rs
@@ -156,4 +156,16 @@ impl Backend for WinRT {
         let playing = state == MediaPlaybackState::Opening || state == MediaPlaybackState::Playing;
         Ok(playing)
     }
+
+    fn voice(&self) -> Result<String,Error> {
+        unimplemented!()
+    }
+
+    fn list_voices(&self) -> Vec<String> {
+        unimplemented!()
+    }
+
+    fn set_voice(&mut self, voice: &str) -> Result<(),Error> {
+        unimplemented!()
+    }
 }