Questions:

In gatherings of women they speak on the microphone. Their voices are heard from far off. Are women allowed to speak on the Deen over the microphone in this manner?

Answer: حامدا ومصليا ومسلما

It is not permissible for women to speak over the microphone in this manner that non mahram men can hear their voices. However, if the volume is low and only the women in the hall will be able to hear and without the microphone they will not be able to hear then there is a leeway in using the microphone for the talk.

And Allah knows best.
(Mufti) Khalid Saifullah (May Allah preserve him.)
Kitabul Fatawa (6/105-106)