The noun phrase that is explained by the appositives is:
"...then I was answered by a voice from within the tomb!"
Explanation:
As stated above about an appositive, you will discover that the appositive, "...- by a cry, at first muffled and broken,..." explains the above noun phrase. It tells the reader the type of voice it heard from the tomb. A noun phrase is known as a phrase that possesses a noun (or indefinite pronoun) and performs the same grammatical function as a noun. These noun phrases can actually function as verb subjects and objects. It can also function as a predicative expression and as the complement of prepositions.
