specifying TTS voice or gender in mrcp SPEAK request

[Killiansirish]

Has anyone had success specifying tts voice or gender using mrcp4j for a SPEAK request?

I've been able to easily specify language via some code like:

mrcpRequest.addHeader(MrcpHeaderName.SPEECH_LANGUAGE.createHeader("fr-FR"));

but I've had problems specifying something like voice-gender......I'm sure I am doing something wrong here but I can't get the headers to come out right for voice-gender......According to
the MRCP spec it *could* be under the mrcpheadername VOICE_PARAMETER but I can't get my
MRCP message to look right.  Has anyone fiddled with different tts voices/genders?  How did you formulate the MRCP SPEAK request?