Take the 2-minute tour ×  Let's assume we follow Rabbi Moshe
Feinstein's ruling that hearing aids are permitted on Shabbat,
but microphones are not.  What about installing an audio
induction loop in the synagogue? It would send out a magnetic
signal that's inaudible to naked ear, but would allow hearing
aids (switched to the right mode) to turn into sound?  Is anyone
aware whether its permissibility has been discussed? Or if it's
been installed anywhere? (It appears this technology is more
popular in the U.K., if that helps)  share|improve this question
חדש אסור מן התורה? –  Seth J Aug 3 '12 at 18:39 add comment  1
Answer  up vote 5 down vote accepted  I wrote to the Zomet
Institute, which works on techno-Halachic issues, and learned
that they have checked and approved such a system, made by
Mehalev, for use in a Jerusalem shul called Kehilat Yedidya.
They were kind enough to provide me with a copy of the approval
letter (.doc).  share|improve this answer Fascinating; though
Zomet is considered on the lenient