public void listVoices(
        com.google.cloud.texttospeech.v1beta1.ListVoicesRequest request,
        io.grpc.stub.StreamObserver<com.google.cloud.texttospeech.v1beta1.ListVoicesResponse>
            responseObserver) {
      io.grpc.stub.ClientCalls.asyncUnaryCall(
          getChannel().newCall(getListVoicesMethod(), getCallOptions()), request, responseObserver);
    }
<pre>
Returns a list of Voice supported for synthesis.
</pre>
java-texttospeech/grpc-google-cloud-texttospeech-v1beta1/src/main/java/com/google/cloud/texttospeech/v1beta1/TextToSpeechGrpc.java