Did that scream startle you?
When most of us hear a scream, our heart jumps and starts racing. But it’s not the volume that spikes our adrenaline, it’s the sound frequency, according to New York University. When study participants were given MRIs, the rougher the scream – and the higher the pitch – the more activity spiked in the brain area linked to fear. That’s why we tend to jump and run when people scream.