Can a myNode : SoNode (coin3d) know its position?

[franco.amato]

Good morning to all,
I'm new of this forum. My goal is add advanced audio features to coin using fmod (audio library). I'm a coin inexpert but not a C++ inexpert. So reading the Inventor book I'm trying to create my own audioNode derived from SoNode.
My big big big problem is whitin audioNode get the 3d position in the scene. The question is can a node knows or retrieve its own position in world coordinates? If yes how can I get this informations? I'm becoming crazy. I don't find this information in the book nor in internet nor from coin mailing list.
I absolutly need from inside audioNode to know the position of audioNode at every frame to update the sound.
Something as:
void audioNode::updateSound()
{
cout << "The position of audioNode is: " << posX << posY << posZ;
}
A person in the mailing list suggest to me to use getMatrix but it doesn't work.
Can I have an urgent help?
Regards,
Franco