For this tutorial, we will set a cassette tape to record its entire A side on the timer. Place a tape in your cassette deck that is connected to your line-in port on your PC through an audio cable. The tape that I will be using is a standard 90-minute audio tape. I use this function for this purpose a lot so that I can start a recording and walk away to work on other projects, knowing that Audacity will automatically stop recording at a set time. If not for this feature, you would have to manually stop the recording and then edit the file to cut off the extraneous blank material.

Launch Audacity and use your mouse to select the Tracks menu. The second option on this menu is Timer Record. Select this option and a new screen will appear. As you can see, you can select a start time and date and an end time and date. These are the setting that you would use to set up an automatic recording sometime in the future. The lowest setting option on this panel is Duration. Because we are just going to do one side of a 90-minute tape, I wil set the recording time to 47 minutes (45 minutes + 2 extra). This gives you a little extra recording time in case there is a little extra audio on the tape. You then hit the Okay button and then hit Play on your cassette deck. Audacity begins the Timer countdown and the recording starts from the moment you hit Okay.

Once the timer completes, you will be left with a 47 minute long audio file that you can save and edit at your leisure.

This tutorial is applicable to both the 1.2 Stable and 1.3 Beta releases of Audacity. You need to have a stereo audio file open in Audacity. Take a look at the waveform of the audio and look to see if one channel is better than the other for your needs. If so, this will be the channel that we will keep. If not, then we can just pick either of the channels to keep and we will discard the other. Once you have settled on the channel that you want to keep, select the drop down menu on the left side of the audio file. In this menu you will see Split Stereo Track. Select this option and you will see your audio file separate into two tracks. These are your left and right audio channels, from top to bottom, respectively.

We now need to discard the channel that we do not want to keep. Hit the X to the left of the drop down menu and this deletes that particular channel. You should now have one channel on your screen. We must now change this from a Left or Right Channel audio file to a Mono file. Go back to the drop down menu and select Mono. This command instantly converts your file into a single channel audio file which will be much smaller than a stereo file. You can now save and export your file into your desired format.

To use this effect, you must have the Audacity 1.3 Beta release which is highly stable. Open the audio that you wish to shorten and select the entire waveform by double-clicking on it. Once you have it selected, go to the Effects Menu and select Truncate Silence. This will pull up a small panel with only two options. These options are Max Silence Duration and Threshold for Silence. The Max Silence Duration refers to how long do you want a pause (silence) to last in your audio file. This number is in milliseconds thus 1000 milliseconds would be 1 second of pause. I generally set mine at 800 milliseconds or 0.8 seconds. This allows for a natural sounding pause without being overly long.

The Threshold for Silence option tells the tool what to consider as silence. If you have a low-level rumble that runs throughout your file, you may need to set this number at -25db or so to treat that as silence. This is the setting that I generally use for all of my files, making slight adjusments up or down to fine tune the file. Once you choose the settings, click OK and the effect will be applied. Check the new length of the file to see if you are happy with it. If not, go back and apply the effect again with a smaller duration for silence. Be sure to listen to a portion of the file afterwards to be sure that it still sounds natural. Unfortunately, this effect can only be applied to Mono sounds files. Stereo files will need to be reduced to Mono before this effect can be utilized.

This effect will change the overall length of the selected portion of the audio file without changing the pitch so that it will not sound like Mickey Mouse. This is a highly effective tool when used correctly and can shorten minutes off of a long audio file and I have a difficult time distinguishing between the original and the edited file.

THE PROCESS

Open the audio file that you would like to shorten (or lengthen) and select the portion of the file that you would like to add the effect to. I typically double-click the waveform and it will select the entire sound file as I want the effect to be applied to the entire file. Once the portion is selected, you go to the Effects menu and choose Change Tempo.

A dialog box will open and you need to choose the amount (percentage) that you want to apply. In my experience, you can change it up to 7 or 8 percent without having too much audible impact. Much more than that, and the sound will move at too great of a pace and it becomes distracting. A handy Preview button is at the bottom of the dialog and you can hear how your amount will sound before applying it to the whole file. Once you choose your amount, select Apply and the effect will be applied to the file.

Once it is done, listen to the end result to be sure that you are happy with the results. If so, save or export the file and you are done.