help to do balancing, mastering ?

i don’t know what technique is this called but,

i have 10 audio.
then i set the volume knob pointed at 5,
the first audio played loudly
the second audio played not as louder as the first one
the third audio played so little, so i have to increase the volume knob to 7
the fourth audio played so very loud, i have to decrease the volume knob to 3

is there any way to balance, or master my 10 audio, so i don’t have to keep changing the volume knob ?

10 audio tracks?
10 audio files?
10 audio CDs?

If you mean 10 audio files, what format are they and what are you playing them on? Does your player support “Replay Gain”? If playing in iTunes, use “Sound Check”.

yep,
let’s say 1.mp3 , 2.mp3 , 3.mp3 . . . . . . . 10.mp3

i am using winamp or Windows Media Player to play those files.

but then, i want to merge those files into 1-combined.mp3 and balance (*or masterIng) the audio, so i won’t be keep changing the volume knob while playing a continuous 1-combined.mp3 . how do i do this in audacity ?

The easiest, and by far the quickest method is to use WinAmp’s “Replay Gain” to adjust the playback level (see: http://forums.winamp.com/showthread.php?t=345520) and use WinAmp’s “play list” feature to combine the MP3s into one play list. This also has the advantage that it does not require re-encoding the MP3s, so not only is it much faster, but it also retains the full sound quality of your MP3s (editing MP3s in Audacity requires that the MP3s are decoded and then re-encoded when you export them, which inevitably causes a slight loss of sound quality - MP3s are designed for small file size and not for re-editing).