Proсessing audio files

Sometimes, there are minor problems with self-recorded audio files, but these are relatively easy to fix. Issues that might require fixing include background noise and extraneous sounds which are audible during the pauses, as well as poor recording quality.

There are many audio editing programs available. You can choose any one of them. For this example, we have chosen Audacity, a free, but sufficiently functional program. Download and install this program. The installation guide for Audacity is included in the distribution package.

The Audacity program

Audacity 2.1.1 for Windows (Windows 2000, XP, Vista, 7, 8) can be downloaded from this link:


Audacity 2.1.1 for Mac OS X (10.5 and higher) can be downloaded from the link:


Additional modules for Audacity

The additional modules may be needed if it becomes necessary to edit audio files in different formats or export the edited audio to mp3 format.

Additional modules for Audacity can be downloaded from the Lame site:


Find the module name among those listed below and download it.

  • A module which makes it possible to export audio files to mp3 format:

Lame_v3.99.3_for_Windows.exe (version for Windows).

Lame_Library_v3.98.2_for_Audacity_on_OSX.dmg (version for Mac OS X)

  • A module which makes it possible to import audio files in different formats, such as AC3, AMR(NB), M4A, and WMA, as well as import audio from video files:

ffmpeg-win-2.2.2.exe (version for Windows). (version for Mac OS X).

Editing audio stories using the Audacity program

Open the Audacity program.

Below, you can see the interface of the Audacity program after the program opens.


Open the audio file that you wish to edit. To do this, in the File menu, select the command Open. The opened file will then be displayed in the form of an audio signal diagram:



Removing the background noise during the pauses

Frequently, during the pauses in an audio recording, you can hear background noise, such as the sound of the microphone or computer fan. The method described below will enable you to remove the background noise from the audio recordings.

Important: if the audio file contains a lot of noise, removing it may significantly reduce the quality of the main recording. In such a case, the audio file should be re-recorded.

The noise removal process consists of two steps – creating a noise profile and removing the noise using the created profile.

  1. Create a noise profile. To do this, perform the following actions:
  • With the mouse, select a noise-free audio fragment, as shown below;


  • From the Effects menu, select Noise Removal;
  • In the window that opens, click on Get Noise Profile.


2. Reducing noise using a profile.

To use the program to remove the noise from all audio files (not just the selected fragment), cut the selection that you made when creating the noise profile. To do this, simply click on anywhere in the diagram. Then perform the following steps:

  • From the Effects menu, select Noise Removal;
  • in the window that opens, click on OK.


Manual removal of noise during pauses

Often, during pauses in an audio recording, background noises can be heard, such as the rustling of pages, coughs, a phone ringing, etc. It a foreign sound is heard only in the intermittent space, then it can be suppressed, thus eliminating the need to re-record the audio file.

This is achieved by reducing the signal to zero in the selected audio fragment.

To reduce the level of the signal in the selected fragment:

  • select the fragment on the diagram;
  • from the Effects menu, select Amplify;
  • in the window, move the amplify slider to the leftmost position, as shown in the figure below;
  • Click OK .


Standardizing the volume

Audio stories can be recorded at different times and under different conditions, which can lead to different recorded files having different volume levels. In order to standardize the volume, you need to perform a normalization procedure.
In order to standardize the volume, perform the following actions:

  • From the Effects menu, select Normalize;
  • in the window that opens, click on OK.

Important: amplifying a weak signal will also amplify any noises. Therefore, if the voice on the tape sounds too quiet, you should record the audio again, having placed the microphone closer to the speaker or having increased the recording level.


Increasing the volume

If a certain segment of the audio recording sounds too quiet, you can increase the volume of this fragment. To do this, perform the following actions:

  • From the diagram, select the fragment of audio file where the volume needs to be increased;
  • from the Effects menu, select Amplify;
  • in the window that opens, click on OK.

The required increase in volume is determined automatically by the program, so there is no need to adjust the settings in the Amplify window.


Important: When changing the volume of individual audio fragments, it is difficult to achieve a uniform volume for vocal tone throughout the audio recording. Sometimes, it is easier simply to re-record the audio.

Removing fragments from an audio recording

Fragments of audio recordings can be deleted when removing intermittent background noise from soundtracks or to shorten lengthy pauses.

To remove a fragment of the audio file, select it with the mouse, and then click on Delete. The selected fragment will be deleted from the audio file.

Saving the final audio file

After you have finished editing the audio file, you need to save it in its final form. To do so:

  • from the File menu, select Export;
  • in the standard dialog box that opens, enter the file name in the Save As field and specify the location where it is to be saved;
  • from the Format list, select MP3 Files;
  • сlick on Save.