Helen had to shout to make herself heard above the sound of

单独看的话确实就是helen was heard
但是现在这里已经有主谓宾了.即
Helen had to shout to make herself heard
对这个句子分析的话.heard 是做补语的.对herself 继续说明.
所以不能再将能成为谓语的be 放进去.
另外你可以make/let sth done ..是什么被做.就固定词组记忆