Hearing aids on Shabbat

Hi,

We are lenient regarding use of a hearing aid on Shabbat. This is different from use of a microphone:

With a microphone we are concerned that people normally connect it only when they need it, so that people will assume it was turned on during Shabbat, but that concern only applies regarding items which make noise, calling themselves to the attention of the public.

The concern of "don't use it lest you adjust it" which we express regarding microphones also applies regarding hearing aids, but a) that is a rabbinic decree and so it may not apply to the uncommon case of a hearing aid (for rabbinic decrees were created only for common cases), and b) the hearing aid involves great need, such as to hear an oncoming car. However, one should do something to prevent actual adjusting.

As far as the concern that one activates a microphone to create a new voice when he speaks, and so one is finishing its construction (makeh b'patish) or actually building it (boneh), neither of these is clear-cut, and this is a case of great need, as we have explained. [There is more here in Rav Moshe's discussion.]

As far as the concern that one's voice causes the electrical current to rise or fall, the prohibition involved is not clear, and this is a case of great need.

Further, sometimes the hearing aid does not pick up the sound, and so its activation is not a guaranteed result of one's action.

Further, if one speaks to people in general, and not only to the person with the hearing aid, then one does not intend to activate it. Indeed, ideally one should avoid speaking to him personally, if at all possible.

(Igrot Moshe Orach Chaim 4:85)

Have a great day,
Mordechai