siren14voice.spp is a package.it contains huge number of voice files.
siren14voice.vtb is an little endian index file.
a data array in the file.
c++ signature:
// 8 bytes alignment
struct vtbfile
{
vtbdata[] Data;
struct vtbdata
{
u32 Offset; //This value >> 4 Is the Offset of a single voicefile...