protected void write(Node action, XHTMLContentHandler xhtml) throws SAXException {
        NamedNodeMap attrs = action.getAttributes();
        Node eNode = attrs.getNamedItem("element");
        String elementType = "p";
        if (eNode != null) {
            elementType = eNode.getTextContent();
        }
        String text = action.getTextContent();
        StringBuilder sb = new StringBuilder();
        Matcher m = Pattern.compile("(?i)([" + vowel + "])").matcher(text);
        while (m.find()) {
            sb.append(m.group(1));
        }
        xhtml.startElement(elementType);
        xhtml.characters(sb.toString());
        xhtml.endElement(elementType);
    }
only parses vowels as specified in "vowel" field.
tika-core/src/test/java/org/apache/tika/parser/mock/VowelParser.java