A ttvf file extension is related to the PlainTalk and used for its data files.
TTVF file extension - PlainTalk Voice data
What is ttvf file? How to open ttvf files?
File type specification:
The ttvf file extension is associated with PlainTalk, part of MacInTalk.
The ttvf files were probably used in some earlier version of MacInTalk.
The program is now integral part of Mac OS X.
This ttvf file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.