In Search of Voice Activity Detection Algorithms - What happens to the frequency or pitch or speech features as speaker moves away from microphone

Actually i am in search of a Voice Activity Detection Algorithm which could distinguish between voice and non-voice

Roughly speaking it must not detect even a bullet sound,even a foot stepping and other non speech activity should only detect people conversation or any one shouting

in that search this question arises in my mind and i want know the effect of noise and distance between speaker and microphone on the speech features like pitch,frequency,cepstrum,zerocrossing rate,power spectral density,entropy etc

if some component wont get distorted i would like to extract that feature and do the activity decision on that

Can any one help me in extracting dominant parameter of speech which would differentiate it from other common sounds even in Lower SNR conditions <0dB

Note:my algorithm expects voice activity happens at a distance of at least 10m away from microphone and continuous generator hum as background noise