What version are you using?
Filename mismatch. The jar includes files "DrillHard.ogg", "DrillSoft.ogg", and "DrillUseLoop.ogg", but the 1.7.10 builds of IC2exp look for files called "drill", "drillOne", and "drillTwo" (without extension). Looking at decompiled code, it seems like "drill", "drillOne", and "drillTwo" are expected to be directly in the "sounds" folder of the jar (rather than a subfolder).
Yeah, the drill sound wasn't playing in 1.7.10. I fixed that in 1.8 iirc.
Yes, I glanced at version 2.3.262 for MC 1.8 via jd-gui, and it was fixed there, but some players (such as myself, and presumably Dagontyr Grim as well) have reasons for staying in 1.7.10.
Renaming and relocating them might work. I haven't tried it myself. I usually just disable IC2 audio in the config so it won't spam the log with error messages about the files being missing, and iirc it also causes the drill to sound like a vanilla pickaxe (so it at least won't be silent, although maybe it's the blocks being broken that cause the sounds)
nope sir it didnt work. my whole computer freezed while loading minecraft 
i renamed the drill sound files in "drill", "drillOne" and "drilltwo" and placed it in the sounds-folder.
is there a chance to get an "update" for 1.7.10 with the sounds?^^
The thing is: A proper fix is not as easy as just renaming a couple of files and be done with it. I spent multiple hours on fixing it in 1.8, so no. We won't see that for 1.7.10.
