Sounds more like a mild epileptic fit, if she was hearing something her ears would likely be straight up or forward, as far as not moving/blinking. I was a caregiver for an epileptic child for a year or so and she would be fine one second then lock up like a bank on a national holiday the next, no noise, no movement, nothing, just blank stare. That would happen up to 15 times a day with this little kid. I was 20 at the time and had gray hairs after three months.
To have Vietnam flashbacks...