If someone response with an incorrect “amen”, does his amen counts like he said amen or is it considered invalid or insignificant? Thank you
When answering amen we are not allowed to answer it too early, (called Amen Chatufa- lit. a grabbed amen, by answering amen before the person saying the bracha finishes saying the bracha) or too late, (called Amen Yisoma- lit. an orphaned amen). A person that says an Amen Chatufa, (or Yesoma) is not considered to have answered amen to the bracha, and it doesn’t count. The Biur Halacha ( 124 D:H V’yesh) says that even if a person is unsure if his amen will be yesoma or chatufa he should better not say it at all
Notrei Amen chap.7 ftnt. 3.