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.
but you're also hearing the sound bouncing around inside your own head, which is conducted by your flesh and bones directly to your inner ear.. That fleshy stuff, according to Green, is better at transmitting low frequencies than high ones, which makes you think your voice sounds lower than it does to other people.