So where are these mythical ER15 earplugs purchased?

It is not the earplugs. It is the filters that go in them :) I am sure you can get custom molded plugs done in Israel. Otherwise you can get an audiologist to take measurements for your ear molds and sent it to Ety or Elacin distributors to get the customized earplugs back in couple of weeks.

P.S. - Just checked. Elacin has representation in Israel:

Rathausmarkt 6
36179 Bebra
T: +49(0)66229167720
I use Alpine PartyPlug earplus - https://www.alpinehearingprotection.com/earplugs/partyplug/ They are invisible to the point, that even people with whom I dance and talk regularly don't know I wear them and when I tell them, they are surprised and want to check.

I like the sound of music in these earplugs. I find them to filter out the annoying high notes a bit more then the lower notes, so I don't get scared when the trumpets kick in.

As with all but the custom-moldel ones, you need to find the right shape and brand for you, because even though they all say that they have anatomical shape, are soft, etc. they will hurt if they are too big or not seal the ear canal correctly (worse sound dampening).
I've just bought these. They are quit big (or I have small ears maybe). I need to test them in party condition now.
For people who may be reading this who think they don't need earplugs, check out this chart that shows the permissible time exposure for each dB level and then next time you go dancing measure the dB level with an app (there are many free apps that do this):
Thanks for sharing this. I've never worn earplugs for dancing before, but just ordered some.
I wear ACS personally moulded earplugs. I can hear the music just at a lower volume. It is very much worth the effort and cost. I have tinnitus from a music career. Use whatever plugs u can afford to buy to protect your hearing.

Dance Ads