please check if the listener is setup correctly:
al.alListenerfv(AL.AL_POSITION, listenerPos, 0);
al.alListenerfv(AL.AL_VELOCITY, listenerVel, 0);
al.alListenerfv(AL.AL_ORIENTATION, listenerOri, 0);
try setting up the source with a distance model of you choice and make sure that all variables used by the distance formula are set correctly
look here for more information about that: http://www.openal.org/oalspecs-specs/attenuation-by-distance.html
last but not least also make sure that you are playing a MONO wav file, openal can't fade a source with Stereo data
i hope this will help you! if not please post more of the source code!
have a nice day!
greetings from austria