public class SomeScript : MonoBehaviour {
    public Animator ellen;
    void Start() {
        GetComponent<Button>().onClick.AddListener(delegate() {
            ellen.SetTrigger(0);
        });
    }
}

public class SomeScript : MonoBehaviour {
    public Animator ellen;
    public float audioDuration;
    void Start() {
        GetComponent<Button>().onClick.AddListener(delegate() {
            StartCoroutine(TriggerAnimation());
        });
    }

    IEnumerator TriggerAnimation() {
        ellen.SetTrigger(0);
        yield return new WaitForSeconds(audioDuration);
        ellen.ResetTrigger(0); //or however you want to return to the idle state
    }
}