I had somewhere between 16-20 ultrasounds. I had a high risk pregnancy and they were keeping a close eye on the baby. Each ultrasound cost around $700 plus the costs from the doctor and lab for reading the results. Luckily our insurance picked up the cost after we paid $2500 out of pocket. Even with all that expense my daughter was totally worth it and is perfect.
Part of the difficulty in answering this question is that depth and cause of coma may vary, and memory is impaired during coma so people might hear but not be able to recall what they hear. In brief: Hard to know. It is hard to know if people in a coma can hear you.
Do deaf people hear an inner voice? I recently lost hearing in my right ear and in this ear all I can hear is the beat of my pulse which only stops when I hold my breath. The constant pumping noise I hear (with my hearing aid in or out) drives me potty. I just wondered if others experience this.