How to decrease volume of a music file?

I’m a complete newbie to Audacity so forgive me if I ask a dumb question. I’ve searched the previous posts and the manual but don’t find what I’m looking for. Of course that may be because I don’t even know the right terms to search.

My OS is Windows Vista Ultimate. I’ve downloaded and installed the most recent version of Audacity v. 2.0.3 from the .exe file.

I need to figure out how to reduce the volume (loudness level) of music files so I can upload them to my teleconference system. I teach virtual classes and when I upload the native music file, it’s way too loud for participants. I want the music to be in the background and soothing, not jarring and overwhelming. My teleconference provider does not provide a way to reduce volume on the uploaded sound files, so I have to figure out how to do it myself.

I don’t want to change anything else about the music file, just the volume level.

If there’s a place in the tutorials or manual that you can point me to, I would be so appreciative.

What format are the music files?

Ooops, sorry. The music files are MP3s, but I can convert them to other formats.

Do you know (or can you find out) if your teleconference system supports “Replay Gain”?
If it does, then you can use programs such as iTunes, or Foobar2000 to adjust the ReplayGain level, which alters the playback level without any loss of sound quality.

No they don’t support Replay Gain. You just upload the file and it is what it is.

That’s a shame.
In that case, Import the file into Audacity (File menu > Import > Audio"), then apply the Amplify effect (Effect menu). Enter a negative number to amplify the audio by. As a rough guide, amplifying by between -6 dB and -10 dB will be about half volume. If you are not happy with the result you can use “Undo” from the Edit menu (shortcut Ctrl+Z).

When you are happy with the result, export (File menu) to create a new audio file. Note that encoding to a compressed formats such as MP3 always reduces the sound quality, so it is better to work with uncompressed audio formats (such as WAV) when possible.

In order to export in MP3 format you will need LAME installed (see here:

I gather you do the file upload frequently.
Hence, it may be worth the trouble to put up a chain command.
Once you have succesfully created a file with the correct volume you can use the values as prototype.
If your sound files are very different in style and genre, it may be better to use another method than simply attenuating the volume by the amplify effect.
Fortunately, Steve has written a replay gain plug-in that you could insert into a chain.
It amplifies the file relatively to the frequency content.
This procedure may produce sound volumes that are perceptionally more “even”, just in case you experience problems with the normal amplification effect.

The Amplify effect should work just fine for what you’re trying to do…

[u]MP3gain[/u] works like ReplayGain, except it adjusts the volume of the actual MP3 file so that it will work with ANY system or player. (And, it works without decompressing/re-compressing the MP3.) You’d have to adjust the settings a bit for lower-level background music, since it’s designed for regular music listening.