What characters are billabling in Text-to-Speech?

Question

What parts of the string we send to SpeakSsmlAsync are billable?
In the code below if text == "Test." the metrics on the portal record 89 characters synthesized. There are obviously more than 89 characters here, so what am I actually being charged for? I'm having trouble getting that number to change in testing.

var speechText = "<speak xmlns=\"http://www.w3.org/2001/10/synthesis\" xmlns:mstts=\"http://www.w3.org/2001/mstts\"xmlns:emo=\"http://www.w3.org/2009/10/emotionml\" version=\"1.0\" xml:lang=\"en-US\">" +
$"<voice name=\"{config["VoiceSettings:Voice"]}\">" +
text +
"</voice></speak>";


await synthesizer.SpeakSsmlAsync(speechText);

Answer 1

Hi, please review the following note in our documentation.

When using the text-to-speech service, you are billed for each character that is converted to speech, including punctuation. While the SSML document itself is not billable, optional elements that are used to adjust how the text is converted to speech, like phonemes and pitch, are counted as billable characters. Here's a list of what's billable:

• Text passed to the text-to-speech service in the SSML body of the request
• All markup within the text field of the request body in the SSML format, except for <speak> and <voice> tags
• Letters, punctuation, spaces, tabs, markup, and all white-space characters
• Every code point defined in Unicode

For detailed information, see Pricing.