The
file opened.You have seen how to open and play audio files. Now let's take a look at how to edit and save files. For these exercises download a sample audio file by clicking on the link below:
Paul Robeson reciting Shakespear's Othello (1958) in mp3 format.
Open the Robeson audio file. You should see something like this:
The
file opened.
Select a portion of the audio and play it back.
The
file with a portion selected for playback.
This is an example of a file containing only spoken words. As you can see, it is easy to pick out the phrases. The waveform representing them shows up in littl clumps and there are spaces of silence in between the phrases. This can make it easy to edit text seemlessly.
Sound Forge, like most programs, will allow you to cut, copy, and paste information. You can use this capability to move a section of audio from one place to another in the same file, to a place in a different file, or to create a completely new file. Let's try it.
With the selection you have just made and played back, pull down the Edit menu and choose Copy.
Copy
the selected portion to the Clipboard.
Now click somewhere else in the waveform window. This will drop the selection and place the cursor in a new spot. Pull down the Edit menu again and choose Paste. The result will probably be difficult to detect without listening to the file again. Some of the reading will be out of order with the rest.
Zoom into the waveform by clicking on the larger of two magnifying glass icons in the lower right corner of the window.
These icons let you zoom into and out of the timeline. You should see something like this. Select one of the small waveform clumps, i.e. a phrase.
Selecting
a phrase.
Play back the phrase. Now pull down the Edit menu and choose Copy. Of course, the usual Ctrl-c for Copy, Ctrl-x for cut, and Ctrl-v for Paste will work too. Now let's open a new empty file by pulling down the File menu and choosing New (ctrl-n). Sound Forge will open the New window:
New
file window.
This window opens whenever you create a new document. It allows you to make choices about what kind of document you want to create. Use the pop-up menus in this window to set the Sample Rate to 22,050, the Bit-Depth to 16-bit, and the Channels to Mono. Then click OK. This will open a new empty window. The cursor will be softly blinking on the far left of the timeline. Paste the phrase into the new window by pressing ctrl-v. This will open the Stereo To Mono window, because we are pasting stereo information into a monophonic file.
Stereo
to Mono window.
Sound Forge wants to know if we want to paste in just the left channel or right channel, or do we want to mix them together? Choose Mix Channels and click OK. This will paste the phrase into the new window (at last!). It should look something like this:
The
phrase pasted into a new document.
Paste the selection into the new document several more times using the same process. If you zoom out, you should see something like this, multiple copies of the phrase next to one another.
Three
phrases pasted.
Play back the document to hear the copies.
Sometimes you may want to delete material from a file. Let's delete the middle of the two phrases above. Select the middle phrase. Make sure that the ends of the selection are in areas where the waveforms are not present, i.e. where the line is thinnest. These are areas of silence.
The
middle phrase selected.
Play the selection to make sure you have just one complete phrase. Adjust your selection until it's right. You can do this by moving the cursor over the left or right edge of the selection. The cursor will turn into a little double-headed arrow and you can drag the selection bigger or smaller. When it's right, press the Delete key and the selected phrase will disappear and you'll see the remaining phrases. The cursor will be blinking where the removed phrase used to be.
Sometimes you may record a little more of a sound than you need. You can use the technique above to delete the extra parts. Be careful to play the selection before you delete it so you don't cut out something you want to keep.
The Process and Effects menus have dozens of commands that can be used to do all kinds of things to your audio, including such standard techniques as: compression, equalization, volume maximization, and many more. Rather large books have been written about how to use all of these, so we'll concentrate on a few useful items.
Sometimes it can be difficult to get the volume levels right on your own recordings. Even professional recordings like the one we are using as an example here may vary in volume. You can correct this to some extent by normalizing the file. To see the effect of this, select one of the remaining phrases in the document we were just working with. Pull down the Process menu and choose Normalize. This opens a complicated-looking box:
The
Normalize controls
Luckily, you don't have to know how all of these controls work because Sound Forge has lots of presets already built-in. Use the menu at the top to choose the Normalize RMS to -10dB (speech) item and click on OK. See the difference between the sample we just normalized and the others? It is much louder now because it has been expanded to fit the available dynamic range without clipping.
The
normalized phrase.
Click somewhere in the window to deselect the phrase and then playback the whole file. Hear the difference in volumes between the normalized and the original phrases? This kind of volume maximization makes your files playback at more consistent volumes so you can avoid the common problem of having some too loud and others too soft.
Sometimes the beginning or end of audio files can be abrupt. It may be useful to be able to fade them in or out to make them less jarring.
Download this music sample to play with. Open the file and play it back. It's a short segment of a local band doing Jimi Hendrix' Foxy Lady.
Select the first half of the clip and choose Process > Fade > In. Play back the selection and hear what's happened to it. It fades in from silence.
Fading
in.
Now select the second half of the clip and this time choose Process > Fade > Out. Now the clip fades in and then fades back out. You can use this technique to make your fade ins/outs as long or short as you'd like.
How you save a file should be determined by what you want to do with it. Sound Forge will save in a wide variety of formats. It is generally best to digitize at full CD-audio quality, whether the source is an audio CD or something you are recording yourself using a microphone. This ensures that the best quality is maintained until you are ready to save. If you download something from the web, you have no control over the quality level, but most of these files will be in some high-bit-rate mp3 format and should sound pretty good anyway.
The two most popular filetype choices for playback in Powerpoint are .wav and .mp3. Both formats support a variety of subformats. You could just save your files as 16-bit/44kHz cd-quality audio files, but you would be wasting a lot of disk space and sacrificing some performance. It might take a long time to load such large files, thus affecting the pacing of your presentation. It is usually best to save your audio files in the MP3 format. These files will be relatively small but will still sound good.
Saving an
MP3 file.
When you save using the MP3 format, there is a pop-up menu called Template in which you can choose which quality level you want to use. Use the 64-128 Kbps settings. It is also possible to save in the Windows Media Audio format using the Windows Media Player. This offers a wide variety of quality levels. When you place the file in PowerPoint however, be sure to use the Insert > Movie from File instead of Insert > Sound from File as PowerPoint thinks of WMA files as "movies" instead of sounds.
| Formats to avoid. In the Windows OS it is not generally possible to guarantee that Quicktime or Real files will play back consistently in PowerPoint. Do not use these. On the Macintosh this in not true. |
If you are making an audio CD you need to save as 16-bit, 44kHz, stereo WAV files.
Saving a WAV
file.