This month, Justin Wilcox has already provided us with some great tips on selecting a microphone and how to get the best recordings. Following his advice will help you get the optimal quality for your recordings.
Today I’ll offer some suggestions that can help you enhance the quality of your voiceover audio after the recording.
Note that the tips discussed here are based on the assumption that you are using a dedicated audio application for your recording and editing chores.
Important: Make a copy of your audio files before trying these tips.
Be sure to use headphones!
Whether you are recording a new file or editing existing ones, the use of headphones is a must — as this is the only way you’ll be able to truly hear the recording (warts and all) versus the use of built-in PC speakers or cheap external speakers. Besides, much of your audience will probably be using headphones, so why not hear what they are going to hear? Although the price and quality of headphones can vary widely, even an inexpensive set ($20 or so) with no bass enhancement should be sufficient for editing audio you’ll be importing into Articulate Presenter and listening to the published output.
The use of audio compression (not to be confused with .MP3 file compression) can be an effective way to enhance the quality of your voiceover recordings. The most immediate benefit of compression is that it helps to maintain a consistent volume level across audio clips, which is why radio stations regularly use it. But an additional benefit of audio compression is that it can add punch to the narrator’s voice.
Here’s a brief explanation of how audio compression works: The software first looks at the range of peaks and valleys in an audio clip (which is natural with the human voice), then narrows this range in volume. Below is an example of how an audio waveform looks before and after compression. Keep in mind that in places where the waveform is taller, the sound is louder. In places where the waveform is shorter, the sound is softer.
As you see in this comparison, the audio clip that was compressed has a greatly diminished number of peaks and valleys, with a majority of the waveform on the tall side. This results in a consistently loud volume throughout the audio clip.
In case you were wondering, compression differs greatly from normalizing audio (known in Articulate Presenter as "optimizing audio volume"), which simply raises the overall volume of an audio clip a certain amount based on its loudest part. Because of the way normalization handles volume levels, it is not uncommon to have a group of files that sound like they are at different volume levels — even when they are all normalized at the same settings. However, normalization is not a bad thing — it can work very well in a number of situations, including working with audio that has already been compressed.
The Levelator is one freeware tool that does a nice job of compressing and normalizing waveforms, and has an easy, drag-and-drop interface with no settings to play with.
One caveat about using compression: if you have a considerable amount of background noise in your recording, applying audio compression can actually raise the volume of this noise. That is why starting with well-recorded audio is paramount.
Let’s face it: Most of us don’t have the luxury of recording in a perfectly quiet environment when we record. A/C vents, fluorescent lights, and microphone/soundcard buzz are among the background noises that can challenge our ability to produce clean-sounding recordings.
The Noise Reduction (NR) feature that is included in many of the mid-level sound applications (approximately $250 and up) can substantially reduce the amount of steady noise in your recordings. Although this function will vary slightly by application, it will allow you to specify the consistent unwanted noise in a audio clip and have it removed throughout. These same applications may also offer other NR functions that are highly effective.
The concept of NR can get complicated and is not something I’ll go into detail here. But you can find a number of tutorials on the web that address using NR with a particular software product.
I should point out that the NR feature is not a miracle worker for every noisy recording, but it can often salvage audio that was once thought unacceptable due to noise. Whether you regularly encounter noise challenges or simply aim to have the cleanest-sounding audio, you might consider investing in software that offers NR functionality.
Add some bass
In the Articulate Forums, we occasionally hear from users who express disappointment about their recordings sounding washed out when compared with their originals. First, let me explain why this happens.
When your audio files are published in Articulate, they are encoded in the .MP3 format, which reduces file sizes to a fraction of the original. To perform this trick, certain frequencies are removed from the audio — with bass frequencies taking the biggest hit (especially with Articulate’s quality settings of 32Kbps and below).
Keep in mind that a considerable loss in quality will always occur when audio is .MP3-encoded to such small file sizes. With that said, there is one little trick that can often help reduce this side effect: Add some bass to your audio before importing into Articulate. It can be particularly effective with recordings of higher-pitched voices.
Most audio editing applications — including the freeware Audacity — have a graphic equalizer function that will give you the ability to add the right amount of bass to your audio clips. Audacity also offers a bass boost feature as well.
After applying bass to a file, do the following:
- Import the file into Articulate Presenter
- Publish the presentation
- Listen with your headphones
If it doesn’t sound right, go back to the original and try it again with different bass settings. Although it may take a few minutes to find the correct bass adjustments, you are likely to obtain some improvement in the sound quality.
Hear for yourself
I encourage you to listen to some audio samples I posted that demonstrate how an audio file can sound when compression, noise reduction, and bass are applied.
All of the samples have been published at a quality setting of 32Kbps. When listening, do you notice a difference? Is there one sample that stands out in your mind?
The tips I’ve provided here are merely suggestions on how you can massage your audio. There is a great deal of subjectivity involved in audio enhancement, and it will require some trial and error on your part. But you’ll find that by trying some of these tricks — and by having a little patience — you can take your audio to the next level.
Phil is a member of Fannie Mae’s Customer Education Group in Washington, DC. His 20 years of experience has involved technical writing, instructional design and standup training, as well as audio production, video production and interactive media development.