I was going through the equipment list and there's no extra information on a signal whistle. I mean, they bother listing that rations would be jerky, dried fruit, and nuts; but they have nothing for signal whistle. I figure this would be rather important information for players and the DM.
I blow my signal whistle. How far does the sound carry? 300 feet? Half a mile? The game doesn't say. Do any other editions provide relevant information on this?