The concept of getting a panic attack in response to listening to some audio is completely foreign to me. Is it normal to have that reaction? It sure seems like it wouldn't be.
IIRC there's some evidence that very low-frequency sounds may cause feelings of anxiety and fear in human subjects. Very low frequency sounds may occur prior to catastrophic events like earthquakes, and some animals have been known to react to it. It's plausible that humans have evolved a similar protection mechanism which has gradually atrophied. That being said, I'm talking about sub-20 Hz frequencies here. I don't think these recordings contain that and I don't think it would be possible to reproduce on regular headphones anyway...
Constant, uniform stimuli for extended periods of time can produce weird effects on the mind. Think about stuff like sensory deprivation, staring at oneself in a mirror, anechoic chambers... And if someone can find a given sound soothing it's not out of this world to think that another sound could have the opposite effect.
