Eliminate "SCRIBBLE" and "AUDIO" from the 'proposed':
<FORM ACTION="url" ENCTYPE="multipart/x-www-form-data"
METHOD="POST">
<p>Say a few words:
<INPUT NAME="voice" TYPE="audio/*" MODE="interactive">
</FORM>
Would be a form that would interactively ask you to talk into the
microphone.
<FORM ACTION="url" ENCTYPE="multipart/x-www-form-data"
METHOD="POST">
<p>Supply an audio or image file:
<INPUT name="data" type="audio/* image/*" MODE="file">
</form>
would be a form that would prompt you to select a .au or .gif or .jpeg
or etc. image file.
Additional advantages are that it would allow the file dialog to
self-select only certain types of files.
I don't know whether application/x-multimedia-tar or
multipart/x-www-form-data or something else is the right type for the
ENCTYPE of the form, though.