Using Rez explode I have looked at the SA *.wav files ( e.g 'south african move fast 00.wav') and they are definitely quieter than the corresponding Indian and Brazilian files. I amplified one of the file so it is similar to the Indian file and renamed it with just one zero not two ( 'south african move fast 0.wav') and I can now hear it - though it still seemed quiet compared to the sound file of the feet on grass and ambient sound etc. So getting rid of the extra 0 in the name seemed to be the difference for me being able to hear the voices. Also I noticed the file structure, number of files and naming is different for the different nationalities - maybe this is deliberate. Also there are spelling mistakes such as 'burning' spelled wrong in the file names. eg 'south african hit burnung vehicle 00.wav'