diff --git a/README.md b/README.md
index f7b882b..8ebb045 100644
--- a/README.md
+++ b/README.md
@@ -68,8 +68,8 @@ Support for custom SSML has been removed since 5.0.0 because Microsoft has taken
 It is possible to make minor changes to the generated speech.
 
     $ edge-tts --pitch=-10Hz --text "Hello, world!" --write-media hello_with_pitch_down.mp3
-    $ edge-tts --rate=0.5 --text "Hello, world!" --write-media hello_with_rate_halved.mp3
-    $ edge-tts --volume=50 --text "Hello, world!" --write-media hello_with_volume_halved.mp3
+    $ edge-tts --rate=-50% --text "Hello, world!" --write-media hello_with_rate_halved.mp3
+    $ edge-tts --volume=-50% --text "Hello, world!" --write-media hello_with_volume_halved.mp3
 
 Keep in mind that the `--pitch`, `--rate`, `--volume`, etc. options are applied to the entire SSML document.
 
diff --git a/src/edge_tts/communicate.py b/src/edge_tts/communicate.py
index 3ea391c..fe8f95f 100644
--- a/src/edge_tts/communicate.py
+++ b/src/edge_tts/communicate.py
@@ -231,15 +231,15 @@ class Communicate:
         ):
             raise ValueError(f"Invalid voice '{voice}'.")
 
-        if re.match(r"^[+-]\d+Hz$", pitch) is None:
+        if re.match(r"^[+-]?\d+Hz$", pitch) is None:
             raise ValueError(f"Invalid pitch '{pitch}'.")
         self.pitch: str = pitch
 
-        if re.match(r"^[+-]0*([0-9]|([1-9][0-9])|100)%$", rate) is None:
+        if re.match(r"^[+-]?\d+%$", rate) is None:
             raise ValueError(f"Invalid rate '{rate}'.")
         self.rate: str = rate
 
-        if re.match(r"^[+-]0*([0-9]|([1-9][0-9])|100)%$", volume) is None:
+        if re.match(r"^[+-]?\d+%$", volume) is None:
             raise ValueError(f"Invalid volume '{volume}'.")
         self.volume: str = volume