I have been to muslim chat rooms where you can hear their voices as they speak through a microphone. They say their voices aren’t soft so it is permissible. They also cite the fact that Hazrat Ayesha Siddique(RAA) used to teach men and they must have heard her voice.
Answer
Kindly refer to the recent AL-Jamiat (Volume 4 No.5) front page:
http://www.jamiat.org.za/al-jamiat/aljamiat.html
Was salaam
Mufti Ebrahim Desai
FATWA DEPT.