Wikispeech should accept SSML input with empty phoneme element text node. (According to [[ https://www.w3.org/TR/speech-synthesis/#edef_phoneme | W3C:s specifications ]], the text node is optional.)
(The problem is that MaryTTS does not accept the empty phoneme element.)
Example of valid phoneme element with empty text node: `<phoneme alphabet="x-sampa" ph="' m V N . k i"></phoneme>`
**Testable URLs:**
**1. With "dummy" text element - working**
https://wikispeech.morf.se/?input_type=ssml&lang=en&input=%3C?xml%20version=%221.0%22%20encoding=%22UTF-8%22%20standalone=%22no%22%20?%3E%3Cspeak%20version=%221.0%22%20xmlns=%22http://www.w3.org/2001/10/synthesis%22%20xmlns:xsi=%22http://www.w3.org/2001/XMLSchema-instance%22%20xsi:schemalocation=%22http://www.w3.org/2001/10/synthesis%20http://www.w3.org/TR/speech-synthesis/synthesis.xsd%22%20xml:lang=%22en-US%22%3E%20%3Cphoneme%20alphabet=%22x-sampa%22%20ph=%22%27%20m%20V%20N%20.%20k%20i%22%3Edummy%3C/phoneme%3E%20%3C/speak%3E
**2. Without "dummy" text element - not working**
https://wikispeech.morf.se/?input_type=ssml&lang=en&input=%3C?xml%20version=%221.0%22%20encoding=%22UTF-8%22%20standalone=%22no%22%20?%3E%3Cspeak%20version=%221.0%22%20xmlns=%22http://www.w3.org/2001/10/synthesis%22%20xmlns:xsi=%22http://www.w3.org/2001/XMLSchema-instance%22%20xsi:schemalocation=%22http://www.w3.org/2001/10/synthesis%20http://www.w3.org/TR/speech-synthesis/synthesis.xsd%22%20xml:lang=%22en-US%22%3E%20%3Cphoneme%20alphabet=%22x-sampa%22%20ph=%22%27%20m%20V%20N%20.%20k%20i%22%3E%3C/phoneme%3E%20%3C/speak%3E
Browser error message: 500 internal server error
Server error message: missing (nothing in wikispeech logs, nothing in marytts logs)