Properties of the SpeechSynthesisUtterance object
lang – A valid HTML language tag; defaults to the document’s value.
voice – A SpeechSynthesisVoice object returned by the getVoices( ) method.
volume – A floating point number between 0.0 and 1.0 inclusive with a default = 1.0
rate – A floating point number between 0.1 and 10.0 with a default of 1.0
pitch – A floating point number between 0.0 and 2.0 inclusive with a default of 1.0.
text – A string value. May be limited to 32k characters.