String argument supplying case information. Can be any of TtsSpan.CaseNominative, TtsSpan.CaseAccusative, TtsSpan.CaseDative, TtsSpan.CaseAblative, TtsSpan.CaseGenitive, TtsSpan.CaseVocative, TtsSpan.CaseLocative and TtsSpan.CaseInstrumental
[Android Documentation]