In The Rising, there is no place to hide, there is no escape, and you will not be rescued. The only hope available for mankind will come from your determination and resilience. The time of avoidance and submission are over. The only option is to resist.
The default Geiger counter in HL2 is being retrofitted with new sounds and the ability to detect Necrotrophs. The detection beats were arranged to mimic human heart beating. This was done in the hopes that it would subconsciously trick your heart into following it's pattern.