JAXB: Unmarshalling of different XML elements with same values

There is a plethora of questions on roughly the same topic, but I couldn't find exactly what I was looking for. My apologies if I missed it.

I'm trying to unmarshal XML files that have common logical elements, but defined with different tags:

Xml input file

<xml>
  <animals>
    <dog>
      <bark>loud</bark>
    </dog>
    <cat>
      <meow>frail</meow>
    </cat>      
  </animals>
</xml>

Both <bark> and <meow> are in fact hiding the same concept, the "pitch" or "sound volume" of the animal, defined as a String.

I could do this:

Animal.java

public abstract class Animal {

    public abstract String getVolume();

}

All it would take would be implementing getVolume() in both Cat.java and Dog.java and return this.bark or this.meow, respectively.

However, it seems cleaner to have a volume attribute in Animal.java and somehow tell JAXB to map both of these fields to it.

Am I overthinking this? How would you implement that?

(Of course, I have no control over the input XML. I would also like to avoid solutions using MOXy if possible, as pushing for another dependency to this project might be difficult.)