diff --git a/google/cloud/texttospeech_v1/services/text_to_speech/async_client.py b/google/cloud/texttospeech_v1/services/text_to_speech/async_client.py
index e8bd0a8b..4eefaf33 100644
--- a/google/cloud/texttospeech_v1/services/text_to_speech/async_client.py
+++ b/google/cloud/texttospeech_v1/services/text_to_speech/async_client.py
@@ -213,15 +213,13 @@ async def list_voices(
             language_code (:class:`str`):
                 Optional. Recommended.
                 `BCP-47 <https://www.rfc-editor.org/rfc/bcp/bcp47.txt>`__
-                language tag. If specified, the ListVoices call will
+                language tag. If not specified, the API will return all
+                supported voices. If specified, the ListVoices call will
                 only return voices that can be used to synthesize this
-                language_code. E.g. when specifying ``"en-NZ"``, you
-                will get supported ``"en-\*"`` voices; when specifying
-                ``"no"``, you will get supported ``"no-\*"`` (Norwegian)
-                and ``"nb-\*"`` (Norwegian Bokmal) voices; specifying
-                ``"zh"`` will also get supported ``"cmn-\*"`` voices;
-                specifying ``"zh-hk"`` will also get supported
-                ``"yue-\*"`` voices.
+                language_code. For example, if you specify ``"en-NZ"``,
+                all ``"en-NZ"`` voices will be returned. If you specify
+                ``"no"``, both ``"no-\*"`` (Norwegian) and ``"nb-\*"``
+                (Norwegian Bokmal) voices will be returned.
 
                 This corresponds to the ``language_code`` field
                 on the ``request`` instance; if ``request`` is provided, this
diff --git a/google/cloud/texttospeech_v1/services/text_to_speech/client.py b/google/cloud/texttospeech_v1/services/text_to_speech/client.py
index 115c173a..742cf1af 100644
--- a/google/cloud/texttospeech_v1/services/text_to_speech/client.py
+++ b/google/cloud/texttospeech_v1/services/text_to_speech/client.py
@@ -398,15 +398,13 @@ def list_voices(
             language_code (str):
                 Optional. Recommended.
                 `BCP-47 <https://www.rfc-editor.org/rfc/bcp/bcp47.txt>`__
-                language tag. If specified, the ListVoices call will
+                language tag. If not specified, the API will return all
+                supported voices. If specified, the ListVoices call will
                 only return voices that can be used to synthesize this
-                language_code. E.g. when specifying ``"en-NZ"``, you
-                will get supported ``"en-\*"`` voices; when specifying
-                ``"no"``, you will get supported ``"no-\*"`` (Norwegian)
-                and ``"nb-\*"`` (Norwegian Bokmal) voices; specifying
-                ``"zh"`` will also get supported ``"cmn-\*"`` voices;
-                specifying ``"zh-hk"`` will also get supported
-                ``"yue-\*"`` voices.
+                language_code. For example, if you specify ``"en-NZ"``,
+                all ``"en-NZ"`` voices will be returned. If you specify
+                ``"no"``, both ``"no-\*"`` (Norwegian) and ``"nb-\*"``
+                (Norwegian Bokmal) voices will be returned.
 
                 This corresponds to the ``language_code`` field
                 on the ``request`` instance; if ``request`` is provided, this
diff --git a/google/cloud/texttospeech_v1/types/cloud_tts.py b/google/cloud/texttospeech_v1/types/cloud_tts.py
index 4360ff61..fb0dd3b6 100644
--- a/google/cloud/texttospeech_v1/types/cloud_tts.py
+++ b/google/cloud/texttospeech_v1/types/cloud_tts.py
@@ -63,14 +63,13 @@ class ListVoicesRequest(proto.Message):
         language_code (str):
             Optional. Recommended.
             `BCP-47 <https://www.rfc-editor.org/rfc/bcp/bcp47.txt>`__
-            language tag. If specified, the ListVoices call will only
-            return voices that can be used to synthesize this
-            language_code. E.g. when specifying ``"en-NZ"``, you will
-            get supported ``"en-\*"`` voices; when specifying ``"no"``,
-            you will get supported ``"no-\*"`` (Norwegian) and
-            ``"nb-\*"`` (Norwegian Bokmal) voices; specifying ``"zh"``
-            will also get supported ``"cmn-\*"`` voices; specifying
-            ``"zh-hk"`` will also get supported ``"yue-\*"`` voices.
+            language tag. If not specified, the API will return all
+            supported voices. If specified, the ListVoices call will
+            only return voices that can be used to synthesize this
+            language_code. For example, if you specify ``"en-NZ"``, all
+            ``"en-NZ"`` voices will be returned. If you specify
+            ``"no"``, both ``"no-\*"`` (Norwegian) and ``"nb-\*"``
+            (Norwegian Bokmal) voices will be returned.
     """
 
     language_code = proto.Field(proto.STRING, number=1,)