2 clarify I think
source | link

The Rivevos Ephraim chelek 5:584:3The Rivevos Ephraim chelek 5:584:3 writes that by krias megila, since if one misses one word of krias megila they are not yotzei  (Mishna Brurah 690:5), accordingly it seems that certainly by parshas zachor which is a Torah obligation if one misses one word he is not yotzei,and it is: like the Sefer Mikraei Kodesh siman 7 writes that, it isn't any lower than megillah.Therefore Therefore one should be careful to listen to every single word.

The Rivevos Ephraim chelek 5:584:3 writes that by krias megila if one misses one word they are not yotzei(Mishna Brurah 690:5) accordingly it seems that certainly by parshas zachor which is a Torah obligation if one misses one word he is not yotzei,and it is like the Sefer Mikraei Kodesh siman 7 writes that it isn't any lower than megillah.Therefore one should be careful to listen to every single word.

The Rivevos Ephraim chelek 5:584:3 writes that, since if one misses one word of krias megila they are not yotzei  (Mishna Brurah 690:5), accordingly it seems that certainly by parshas zachor which is a Torah obligation if one misses one word he is not yotzei: like the Sefer Mikraei Kodesh siman 7 writes, it isn't any lower than megillah. Therefore one should be careful to listen to every single word.

1
source | link

The Rivevos Ephraim chelek 5:584:3 writes that by krias megila if one misses one word they are not yotzei(Mishna Brurah 690:5) accordingly it seems that certainly by parshas zachor which is a Torah obligation if one misses one word he is not yotzei,and it is like the Sefer Mikraei Kodesh siman 7 writes that it isn't any lower than megillah.Therefore one should be careful to listen to every single word.