Hack58.Add Special Effects

Hack 58. Add Special Effects

Use plug-ins to create unique sonic effects in your podcast.

Today's digital editing tools [Hack #50] make creating sound effects or altering the feel of your sound a snap. How many or how much of each effect you use depends on the type of sound you are going for. For a voice podcast, you should probably go with just a slight reverb to add some depth to your voice or to simulate a larger space. A music show might use all of these effects at various times.

Understanding effects starts with understanding wet and dry. An effect is referred to as wet when it's fully applied to the target signal. It's dry when it's applied sparingly. A signal that's processed heavily is often referred to as wet.

8.10.1. Reverb

When you talk, your voice is reflected back at you off the walls, the floor, and the ceiling. The shape and size of the room, as well as the texture and materials of the walls and the floor, all add to the room's sonic character. For example, your shower is very active and has a lot of reflectivity because of the tight space and the materials on the walls. A closet will be less reflective because the clothes will deaden the sound.

This effect is known as reverberation, or reverb for short. Using a software reverb adds a simulated space to a signal. Simple filters allow you to control just the size of the room, and more complex commercial filters actually simulate complex spaces such as Carnegie Hall. Specialized packages even include hardware that can sample a space and then reproduce it as filter settings.

Reverb can easily be overdone. It's an effect that you should use sparingly. An overly wet reverb effect sounds very unnatural. Just a little can add depth and warmth to a voice.

Doug Kaye from IT Conversations (http://itconversations.com/) recommends having a friend do your reverb and compression settings for your voice. This will keep you from building a filter that ends up making your voice sound unnatural.

8.10.2. Flanger and Chorus

Reverb, flanger, and chorus are all in the delay effects family. Each takes a running copy of the signal and then plays it back, sometimes with the gain altered, later in the signal. The amount of this delay, between a peak in the signal and when the copy of the peak in the signal occurs, is what delineates each effect. Reverb, which simulates the acoustics of a room, has a very short delay. Flanger, which is a rock 'n' roll guitar effect, is a little longer. Chorus, which simulates multiple voices, is longer still.

Flanger and chorus are useful when you are doing a music show and you want to make some of your own music or do some fun effects stuff with your vocals.

8.10.3. Diffing

Diffing takes a copy of a signal from a portion of one track and copies it onto another track slightly shifted in time. This has the effect of fattening up the sound of particular words or phrases.

Figure 8-23 shows the signal in Audacity that I diffed. I started by creating a second track and copying the portion of the signal that I wanted to accentuate. Using the Move tool, I positioned this copied version just a bit ahead of the original signal. To make that process easier, I used the Zoom tool to zoom in on the two signals.

Figure 8-23. Diffing in Audacity

In addition to varying the position of the copy to add more or less of a sonic doubling, you can also use gain enveloping, as I have here. This enveloping allows me to change the intensity of the effect at various points in the word. In this example, I accentuated the start of the word and let the effect trail off toward the end.

Diffing is very time consuming to get it to sound the way you want. It's an ideal effect to add some more punch to promos.

8.10.4. Pitch Shifting

You can lower the pitch of your voice and sound like James Earl Jones, or raise the pitch of your voice and sound like The Chipmunks, by using pitch shifting. Audacity's Change Pitch effect gives you control by percentage, or you can raise or lower by semitones.

8.10.5. Changing Speed

If someone talks too fast or slow, you can use a speed filter to speed them up a little or slow them down. Audacity supports this with two filters. The Change Speed effect has a percentage change going up to speed up a sound, or down to slow it down. The tone will change as you speed it up or slow it down. The other effect, named Change Tempo, speeds up or slows down the signal without altering the tone.

8.10.6. Excitifiers

The aural exciter is a single effect that uses a set of filters to brighten up a dull sound. This is done by adding harmonics so that it is more acoustically interesting to listen to. This is one effect that I recommend simply sitting down and playing with. Run the effect over and over on a short sentence to see what you can get from the different settings.

Excitifiers are a bold journey into the murky realm of psychoacoustics where signal differences are not always quantifiable but are in the ear of the beholder.

8.10.7. Silence

Every sound editor supports the Silence function that replaces the selected signal with silence. This is a handy tool for manually removing noise segments from individual tracks that you are going to merge into a single mono or stereo track.

The last word in altering sound should always be to compare what was there before with what you have now. Listen to the two and make sure you made an improvement. It often helps to have someone else listen to both for the first time, without letting them know which has been altered.

8.10.8. See Also

• "Choose the Right Audio Tools" [Hack #50]

• "Juice Your Sound" [Hack #51]

• "Maintain the Gain" [Hack #56]

• "Build a Sweet Sound" [Hack #57]