mdbk77 wrote:But if the original is Mono, then why did it play in both speakers?
in a stereo file you have 2 audio "channels". One channel is set to play through only the Left output (left speaker/headphone) and the other set to play only through the right. (It can sometimes be a little more complex than that with MP3s and other compressed audio files, but let's not worry about that just now).
With a "mono" recording, there are 2 ways that it can be represented. For audio files, "mono" usually means just a single audio channel that is set neither to Left or Right, but is set as "mono". When you Import this type of mono file into a new empty Audacity project, Audacity
should show it as a track with just one channel. If you open Audacity and use one of the "Generate" functions (Generate menu), then Audacity creates just such a mono track, and if you click on the name of the track you will see in the drop down menu that it is set to "mono".
Now I said that there are 2 ways to represent mono audio. The other way is as 2 identical channels, such that there is a Left channel that is identical to the Right channel. If you listen to a radio that is tuned to a station on "long wave" (AM radio), then the audio is mono. It is transmitted as a single audio channel, but when you listen to it, you are listening with 2 ears, so your brain is receiving 2 channels (left ear and right ear) and if you listen through headphones you will notice the strange effect of the sound being in the middle of your head.
If you play a single channel audio file in a media player, because it is not specified as being Right or Left, the media player should simply play the file through both speakers.
Here's a little experiment to try that should demonstrate this practically - this is bet if you listen through headphones.
1) Open Audacity
2) From the Generate menu, generate a tone.
3) Play the tone, and if you are listening through headphones and everything is set up correctly, the tone should sound like it is in the middle of your head.
4) Click on the track name and in the drop down menu you will see that it is set to "Mono".
5) Now, from the drop down menu, set the track to "Left channel" and listen to it again. You should hear that it plays only through the left headphone (if it plays through the right headphone, you have your headphones the wrong way round).
6) Now press Ctrl+D (this will duplicate the track).
7) Click on the name of the duplicate track and set it to "Right channel".
8) If you play this again, it should sound just the same as the original mono track.
9) Use the "Solo" button on the tracks so that you can listen to one, then the other track. You will hear that one track plays to the left ear and the other plays to the right, but when both tracks are enabled you can hear it through both and it sounds mono. The original single channel mono track played identically through both left and right, and our new identical pair also plays identically through both left and right.
Earlier I said that Audacity should import a mono file as a single channel track. I have noticed that in some situations it doesn't. I'm not quite sure why it doesn't and it should not really do this, but with some files on some machines I have seen it happen. What it does instead is to import it as 2 identical channels - a stereo track with both left and right the same. In Audacity 1.3 it is very easy to correct this (I think this is slightly different in Audacity 1.2). You simply select "Stereo Track to Mono" from the "Tracks" menu and it mixes the two tracks into a single channel mono track.
If you then Export the mono track as an MP3 file, it should export it as a single channel mono track and enable you to increase the compression settings to get a smaller file. However, things can go wrong here as the encoding is not done by Audacity, it is done by LAME, and depending on exactly which version of Lame is being used, you can get incorrect settings. Personally, if the encoding settings are important to me, I prefer to Export as a WAV file, then use LameDropXPd to encode the file. LameDropXPd is a very good (free) MP3 encoder that also uses Lame, but because it is specifically an MP3 encoder program, it is more flexible and easier to specify exactly what compression settings you want. There are plenty of other excellent free stand-alone MP3 encoders that have advantages over the basic settings that are available in Audacity 1.2. MP3 encoding in Audacity 1.3.7 is better than in 1.2 and offers more options (such as VBR).
