the attenuation value is the distance

the lower it its, the further you can hear the sound, ATTN_STATIC (1.25) can be heard really close, but not as close as ATTN_IDLE (2.0)... use ATTN_NONE (0.0) and see what happens when you place an emit sound in the far end of the map
also, you can not do emit sound with mp3, you can do a client command with mp3...
PHP Code:
client_cmd("mp3 play ^"sound/path/music.mp3^"")
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