I suspect you are making a common mistake about Node values. The Element "AUD_EVENT_TXT" has a Text Node as a child.
Element nodes return null from a call to getNodeValue() - Text nodes return the text I suspect you are looking for.
The JavaDocs for the org.w3c.dom.Node interface have a marvelous table describing what all the different kinds of XML DOM Node return for value, name, etc.
Anybody working with XML in
Java needs to get very familiar with this table.
Bill