Limited to 2000 characters when using ssml

[sylarlocke]

Hello, I have been using the library and it works correctly, but when I try to apply the TextToSpeech::ssml() method if there is more than 2000 characters (I have verified it and the error is due to the characters) it throws me the following error message:
http://prntscr.com/1JW3E4ZRCp-d

The thing is that without using "ssml" I don't have any character limits, or at least for now.

*The tags open "speak" and close "/speak" are added in var $text_polly, but are removed by the code editor adding it here on Github.

$text_polly = 'I add text here...<amazon:effect vocal-tract-length="+18%"> Vocal tract change!</amazon:effect>up to 2000 characters or less does not give an error, but more 2000 characters show error message';

$voice = 'Lucia';
$language = 'es-ES';
$options = ['voice' => $voice];
$path = TextToSpeech::language($language);
$path = TextToSpeech::ssml()->saveTo('/mp3/en/test-ssml')->convert($text_polly, $options);

I have been testing on the Amazon Polly AWS page and there it works for me to add more than 2000 characters.

Could it be limited in the API itself?