Q. There is a totally new apparatus in the market to amplify the voice of those who have a very low one. It uses something similar to a blue tooth and amplifies one's low voice. If someone uses it, does he have to turn it off when he is counting Sefira, since as mentioned on a question above, unnatural voices such as the ones created by vibrators are not good for counting Sefira?
A. Horav Dovid Pam Shlit'a compared the above apparatus to one speaking in a microphone.
On question 482 we were asked: "Since we do not fulfill our obligation with a bracha recited over the telephone, why do people answer amen when the sheva brachot under the chupa or at the seuda are said over the microphone? Are the chatan and kalah yotze if they hear the bracha mainly from the loudspeakers?
To what we answered: As is mentioned in Talmud (Suka 51b) in regards to the flag signals of the well attended Great Synagogue of Alexandria, we do answer amen even when we did not hear at all the recited brocho, as long as we are aware which brocho is being recited. So rules Igrois Moishe (O.H. 4: 91: 4) in regards to answering amen for a blessing heard via telephone or loudspeaker.
Horav Shlomo Miller’s Shlit”a opinion is that under the chupa, where there is a requirement to be yotze with the first two brochos of the Rov, even when the Rov who performs the ceremony is reciting the brochos using a microphone, since he is so close to the Chosson and Kallah and they could hear him clearly anyway, they comply with his blessings, as they do not need the loudspeakers at all."
Horav Shlomo Miller’s Shlit’a opinion is that in our case one can comply with the mitzva of counting since that was after all his intention and the words did come out of his mouth.
Rabbi A. Bartfeld as revised by Horav Dovid Pam, Horav Aharon Miller and Horav Chanoch Ehrentreu Shlit'a