993. Listening to the Reader

141:13 The one reading the Megillah must have the intention to include all those listening. The listener must likewise intend to fulfill his obligation, and he must listen to each and every word. If he misses even one word, he has not fulfilled his obligation. The one reading must therefore be very careful that when noise is made to drown out Haman's name, that he remains silent until the noise has completely stopped. In any event, it is best for each person to have a kosher Megillah so that he can read each word quietly by himself, in case he misses a word from the reader. Similarly, it would be preferable for every woman in the women's section to have a kosher Megillah to read from, because it can be hard to hear there and women are obligated to hear the Megillah, just as men are. (One can also read along in a printed Megillah or Chumash and fill in any words he or she may not be able to hear - Mishnah Brurah 690:60.)

Regarding if they did not yet sanctify the new moon and they finally saw it when it was time for Megillah reading, see the end of chapter 97.

141:14 The reader must recite the names of Haman's ten sons (Esther 9:6-10), as well as the word "ten," all in a single breath in order to proclaim that they were all killed and hanged as one. The optimum practice is to say from "five hundred men" in a single breath. After the fact, one has fulfilled his obligation even if he paused in between the sons of Haman. The practice they follow in some communities, where the entire congregation recites the names of Haman's ten sons, is not proper. Rather, the reader should recite them alone and the congregation should listen, as is the case with the rest of the Megillah. When the reader recites, "That night, sleep eluded the king..." (Esther 6:1), he should raise his voice, because that's where the main part of the miracle begins. When he recites "this letter" (Esther 9:26), he should rustle his Megillah.