NewB Question~ Judging distance by Sound? Attack strategy Question

[Shan~Man]

Any tips for judging distance to target based on sound only? Direction is not a problem. Example: Hearing enemy chopper land over crest of hill and whether nades would be effective from your position or?? (of course you have checked the map 1st for friendly's)

While I'm at it:
Suggestions on attacking: You hear a enemy chopper land and deploy troops over the crest of a hill and you have not been seen in open terrain.

[Heavy Death]

By years of playing and knowing the sound distances.

[QuickLoad]

Judging distance via sound is pretty hard, itll take you a lot of years.

Use sound to find the direction of the target,
use your eyes to estimate the distance to a target(or find landmarks and use your map).