public static com.google.cloud.texttospeech.v1.StreamingSynthesizeConfig getDefaultInstance() {
    return DEFAULT_INSTANCE;
  }
<pre>
Optional. The pronunciation customizations are applied to the input. If
this is set, the input is synthesized using the given pronunciation
customizations.

The initial support is for en-us, with plans to expand to other locales in
the future. Instant Clone voices aren't supported.

In order to customize the pronunciation of a phrase, there must be an exact
match of the phrase in the input types. If using SSML, the phrase must not
be inside a phoneme tag.
</pre>

<code>
.google.cloud.texttospeech.v1.CustomPronunciations custom_pronunciations = 5 [(.google.api.field_behavior) = OPTIONAL];
</code>
java-texttospeech/proto-google-cloud-texttospeech-v1/src/main/java/com/google/cloud/texttospeech/v1/StreamingSynthesizeConfig.java