diff --git a/src/backends/android.rs b/src/backends/android.rs
index 3f6d422..bc54ad4 100644
--- a/src/backends/android.rs
+++ b/src/backends/android.rs
@@ -250,6 +250,7 @@ impl Backend for Android {
             utterance_callbacks: true,
             voice: false,
             get_voice: false,
+            synthesize: false,
         }
     }
 
@@ -284,6 +285,10 @@ impl Backend for Android {
         }
     }
 
+    fn synthesize(&mut self, text: &str) -> Result<Vec<u8>, Error> {
+        unimplemented!();
+    }
+
     fn stop(&mut self) -> Result<(), Error> {
         let vm = Self::vm()?;
         let env = vm.get_env()?;
diff --git a/src/backends/appkit.rs b/src/backends/appkit.rs
index cf1375a..ddc5c22 100644
--- a/src/backends/appkit.rs
+++ b/src/backends/appkit.rs
@@ -123,6 +123,10 @@ impl Backend for AppKit {
         Ok(None)
     }
 
+    fn synthesize(&mut self, text: &str) -> Result<Vec<u8>, Error> {
+        unimplemented!();
+    }
+
     fn stop(&mut self) -> Result<(), Error> {
         trace!("stop()");
         unsafe {
diff --git a/src/backends/av_foundation.rs b/src/backends/av_foundation.rs
index a64d9b4..69379c4 100644
--- a/src/backends/av_foundation.rs
+++ b/src/backends/av_foundation.rs
@@ -169,6 +169,7 @@ impl Backend for AvFoundation {
             voice: true,
             get_voice: false,
             utterance_callbacks: true,
+            synthesize: false,
         }
     }
 
@@ -205,6 +206,10 @@ impl Backend for AvFoundation {
         Ok(Some(UtteranceId::AvFoundation(utterance)))
     }
 
+    fn synthesize(&mut self, text: &str) -> Result<Vec<u8>, Error> {
+        unimplemented!();
+    }
+
     fn stop(&mut self) -> Result<(), Error> {
         trace!("stop()");
         unsafe {
diff --git a/src/backends/speech_dispatcher.rs b/src/backends/speech_dispatcher.rs
index b3034a1..b91bd3b 100644
--- a/src/backends/speech_dispatcher.rs
+++ b/src/backends/speech_dispatcher.rs
@@ -85,6 +85,7 @@ impl Backend for SpeechDispatcher {
             voice: true,
             get_voice: false,
             utterance_callbacks: true,
+            synthesize: false,
         }
     }
 
@@ -108,6 +109,10 @@ impl Backend for SpeechDispatcher {
         }
     }
 
+    fn synthesize(&mut self, text: &str) -> Result<Vec<u8>, Error> {
+        unimplemented!();
+    }
+
     fn stop(&mut self) -> Result<(), Error> {
         trace!("stop()");
         self.0.cancel()?;
diff --git a/src/backends/tolk.rs b/src/backends/tolk.rs
index 056d75e..408c1f5 100644
--- a/src/backends/tolk.rs
+++ b/src/backends/tolk.rs
@@ -39,6 +39,10 @@ impl Backend for Tolk {
         Ok(None)
     }
 
+    fn synthesize(&mut self, text: &str) -> Result<Vec<u8>, Error> {
+        unimplemented!();
+    }
+
     fn stop(&mut self) -> Result<(), Error> {
         trace!("stop()");
         self.0.silence();
diff --git a/src/backends/web.rs b/src/backends/web.rs
index 578a213..e1c140f 100644
--- a/src/backends/web.rs
+++ b/src/backends/web.rs
@@ -59,6 +59,7 @@ impl Backend for Web {
             voice: true,
             get_voice: true,
             utterance_callbacks: true,
+            synthesize: false,
         }
     }
 
@@ -121,6 +122,10 @@ impl Backend for Web {
         }
     }
 
+    fn synthesize(&mut self, text: &str) -> Result<Vec<u8>, Error> {
+        unimplemented!();
+    }
+
     fn stop(&mut self) -> Result<(), Error> {
         trace!("stop()");
         if let Some(window) = web_sys::window() {
diff --git a/src/backends/winrt.rs b/src/backends/winrt.rs
index ceb5f00..85fb1ae 100644
--- a/src/backends/winrt.rs
+++ b/src/backends/winrt.rs
@@ -156,6 +156,7 @@ impl Backend for WinRt {
             voice: true,
             get_voice: true,
             utterance_callbacks: true,
+            synthesize: false,
         }
     }
 
@@ -207,6 +208,10 @@ impl Backend for WinRt {
         Ok(Some(utterance_id))
     }
 
+    fn synthesize(&mut self, text: &str) -> Result<Vec<u8>, Error> {
+        unimplemented!()
+    }
+
     fn stop(&mut self) -> std::result::Result<(), Error> {
         trace!("stop()");
         if !self.is_speaking()? {
diff --git a/src/lib.rs b/src/lib.rs
index 76c7b94..98b723e 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -162,6 +162,7 @@ unsafe impl Sync for UtteranceId {}
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub struct Features {
     pub is_speaking: bool,
+    pub synthesize: bool,
     pub pitch: bool,
     pub rate: bool,
     pub stop: bool,
@@ -217,6 +218,7 @@ pub trait Backend: Clone {
     fn id(&self) -> Option<BackendId>;
     fn supported_features(&self) -> Features;
     fn speak(&mut self, text: &str, interrupt: bool) -> Result<Option<UtteranceId>, Error>;
+    fn synthesize(&mut self, text: &str) -> Result<Vec<u8>, Error>;
     fn stop(&mut self) -> Result<(), Error>;
     fn min_rate(&self) -> f32;
     fn max_rate(&self) -> f32;