Scar tissue on the ear drum is usually caused by repeated ear infections. The scar tissue can lead to difficulty hearing and eventually ruptured ear drums. Surgery is one means of avoiding progressive hearing loss or ear drum rupture. No patients have reported taking Scar tissue removal (eardrum).
USCIS normally responds to RFE's within 60 days, however they do not have processing times on how long it takes them to respond. It can be longer than that. I would call the USCIS number: 1 (800) 375-5283 and submit a service request, if you do not hear from them soon.
For your own security and success, only one conference host is permitted in each call. Yes. Participants can call up to 10 minutes before the host enters the conference call. Early participants are placed in a waiting room with on-hold music until the host joins the call. If the wait time is exceeded, they will be prompted to confirm the conference time with the host and call back.