Is there an easy way to “normalize” the volume range in a playlist - consisting of many individual tracks - so that the maximum and minimum levels are inside some range? The idea is that I don’t want to set up the volume on my speakers so that I can hear one track clearly, and then have another track blow up in a huge volume or the other way around, if I set up the speakers for the highest volume, I can hardly hear some of the other tracks. Thanks in advance for anyone helping me here - I am a new user and not very well versed in these technologies.
Dani
The best, quickest and easiest way, if supported by your media player, is to use ReplayGain (http://en.wikipedia.org/wiki/ReplayGain) or Sound Check (http://support.apple.com/kb/ht2425)
If there are too many files to normalize individually with Audacity you can normalize with your player. I use the free AIMP3 player which has regular normalize and ReplayGain. With ReplayGain you have to add data to all the tags you want to normalize. I used foobar2000 to accomplish this when I was experimenting with it. I’ve had mixed results with players that normalize “on the fly.” The volume tends to go up and down all the time and it’s really noticeable. To me there’s no substitute for normalizing your files in Audacity. You could try a few of the worst ones and see how it goes. After awhile it doesn’t take all that long. 
Thanks for the replies - is there a way to normalize inside Audacity? I don’t think using the player will work for me - I want to use the playlist on my computer as well as on an external mp3 player. How to do it in Audacity? I am hoping these is some sort of a “bulk” mode when you can do this for many files but perhaps this is too good to hope for - perhaps in some future version?
You can Normalize the “amplitude” (how “big” the waveform is vertically) with the “Normalize” effect: http://manual.audacityteam.org/o/man/normalize.html
Note that tracks having the same peak amplitude does not necessarily mean that they will sound the same “loudness”.
The player option is still the best. You can load all files into Foobar2000 (or similar) and scan for replay gain (context menu or right mouse button).
You can apply the found values either permanently (modifies the audio) or as entries in the mp3-tag.
You can Import multiple files then normalize one at a time or all at once, but there are some downsides I’ll explain in a minute. To Import, use File>Import>Audio then navigate to the files. Select all the ones you want to Import then click Open. Or alternatively you can go to the folder where the files are stored, select them, and drag them into Audacity. Once you have them in the program you can select them individually by clicking the Track Control Panel to the left of the Waveform of each track, or select them all by using Edit>Select>All, or, just press Ctrl+A.
Now the downsides. When you Import multiple files, Audacity sees it as one project and that presents a problem when you go to Export, or save, the files. If you Export them individually, Audacity will try to save every one with the file name and tag data of the first file, so they all have to be edited one by one with the correct info. You can overcome this to a certain extent by Exporting them all with File>Export Multiple. You can choose to retain the correct file names, but it still has a problem getting the tags correct. If the tag data isn’t important, then this might be the way to go.
But there are still a couple of other issues. As steve mentioned, perceived loudness is sometime different from actual amplitude, so normalizing them all to the same amplitude may no solve your problem. Also, if a file has one very high peak, that peak will normalize to the max amplitude but the rest of the file will be kept artificially low because of this. The only way to overcome this is to deal with each file individually then see how it sounds.
I’d just work on the ones that are giving you the most grief, then after you’ve got a better handle on what you’re doing you can figure out what the best solution is for you.
[u]MP3Gain[/u] is a version of ReplayGain that changes the volume of the actual MP3 file (so of course, it works with any player).
Notes & comments:
Since many (most?) quiet sounding songs are already peak-normalized (AKA maximized), you can’t boost those quiet songs without clipping/distortion. That means the only way to match volume (no matter what tool you are using) is to reduce the loud-sounding songs. Overall, many (most?) of your songs will be quieter, and this bothers some users.
You can make quiet songs louder without clipping if you use dynamic compression. (Audacty has a compressor and there are optional plug-ins.) But if you want to maintain the dynamic contrast in the music, you’ll have to match volumes by making the loud-sounding songs quieter.
Even with the overall volume reduction, a few quiet-sounding files won’t be volume-matched without clipping. You can set either ReplayGain/MP3Gain to allow clipping, or leave the defaults and compromize the loudness-matching on these few songs.
MP3Gain works without decompressing/re-compressing the MP3 data. So unlike a regular audio editor, your files don’t go through a 2nd lossy-compression process when you save the modified MP3.
Due to the limitations of MP3, you can only change the “gain” in 1.5dB steps (without decompressing/re-compressing). So, some of your files will be mis-matched by up to 3/4ths of a dB. (But, even if ReplayGain/MP3Gain makes a “perfect” match, human perception of loudness won’t agree completely with MP3Gain anyway.)
MP3Gain writes some sort of change-tag in the MP3 file so knows how much change was made so it is reversable. It’s probably still a good idea to keep an back-up copy of the un-MP3Gained original.