The first thing that you need to do is create a Stereo Track so that there is somewhere for the synthesized audio to live. I normally use a Mono Track for sound effects, such as the Fire and Explosion generator, but some of these effects require a Stereo Track, such as the Oxygene Wave generator. All of them utilize a Stereo Track if it is present; I opted to use a Stereo Track so that you can see the Generate plug-ins that support it. If a Stereo Track is supported, the Left and Right Channel data samples will look different; if only Mono Tracks are supported, the Left and Right Channel data is identical.

Launch Audacity 2.1 and use the Tracks ➤ Add New ➤ Stereo Channel menu sequence to add an empty Stereo Track to your new digital audio synthesis project (see Figure 11-5).

Select the Generate menu and the Surf [Oxygene] option, which opens the Surf [Oxygene] dialog (see Figure 11-6).

I used the stereo Surf output option, with an 80% spread, 0 fade effect, 10 cycles, pink noise generation, 100 Hz start frequency and 1000 Hz ending frequency, 1.5 second sweep duration, 2 seconds of post-sweep silence, a 300 Hz Crash filter frequency, 24 decibels of Crash bass frequency boost, and a Crash duration of 5 seconds.

As you can see in Figure 11-7, the Oxygene Wave waveform synthesis signature is very unique and different across the two channels. Use the play button to preview crashing ocean waves!

Next, let’s take a look at a more useful tone generator, Click Track, the virtual metronome for Audacity.

If you’re recording your instrument and not your voice, Audacity has a useful Click Track (metronome) tone generator that comes preinstalled. You can utilize it to make sure that you are on a beat. It allows you to set the Tempo in BPM (beats per minute), the beats per measure (usually 4), the number of measures, the Click Track duration, and the metronome tone duration in milliseconds. You can also specify start time offset, click sound, click resonance, and click pitch, all of which you can see in the Click Track dialog shown in Figure 11-8.

I accepted the default setting values and clicked the OK button to generate the Stereo Click Track shown in Figure 11-9. Click the play button to preview the metronome click track now.

It’s important to note that you can use a Mono Track for this metronome click-track functionality. So if you’re going to use it when recording instrument performances, use the Tracks ➤ Add New ➤ Mono Track menu sequence, rather than using a Stereo Track, although that works as well.

Before you start recording instrumental music tracks in Audacity, you should use the Tuning Fork generator to make sure that your instruments are in tune. This tone generator allows you to set the Tone duration, which I set to 1.0 second; Constant volume or a fade out, which I selected to simulate a real-world tuning fork; and MIDI note or (optional) frequency. I used the default MIDI note of 69, as you can see in the Tuning Fork dialog in Figure 11-10. If you want to use a C note (music, not money) for a tuning fork, use a MIDI note value of 60.

I accepted the default values and clicked the OK button to generate the Tuning Fork track shown in Figure 11-11. Click the play button to preview your tuning fork tone now.

It’s important to note that you can use a Mono Track for this tuning fork track functionality. You can also delete it once you are finished using it, in order to save system resources such as memory and CPU processing cycles.

Next, let’s look at David R. Sky’s Fire and Explosion generator, a virtual special effects shop in Audacity 2.1! You can use this FX tone generator to create special audio effects for your games.

The Fire and Explosion generator allows you to set the type of audio effect, sound duration, attack time in milliseconds, explosion decay in milliseconds, decay percentage, cut-off frequency, filter quality, Bass boost frequency and decibels, and clipping percentage. I used the defaults, as you can see in the Fire and Explosion dialog shown in Figure 11-12.

I accepted the default setting values and clicked the OK button to generate the Explosion effect track (see Figure 11-13). Click the play button to preview th e explosion effect.

Next, let’s look at Steven Jones’ KLSTRBAS generator, which stands for cluster bass.

According to KLSTRBAS tone generator author, Steve Jones: “KLSTRBAS generates dense sounds by combining several waveforms with a fixed frequency ratio between them. Early Roland drum machines created cymbal sound in part by combining multiple square waves with non-integral frequency ratios. The combined signal was then high-pass filtered to produce a very dense cluster of high frequency harmonics. The genesis of KLSTRBAS was a failed attempt to create cymbal sounds using this technique.”

As you can see in Figure 11-14, the KLSTRBAS dialog allows you to set your MIDI key (note value), Decay value, Fractional Decay value, Density value, Detune value, Flange value, and Wave table indicator value.

The wave table indicator can be set to one of four value settings: 0 indicates a sine wave table, 1 indicates a triangle wave table, 2 indicates a square wave table, and 3 indicates a saw wave table.

As evident in the KLSTRBAS dialog, you have a great deal of variation in creating cool tones with this generator. I set the A3 note is the MIDI key, a 2-second decay, a fractional decay value of 0, a density value of 4, a detune value of 0, and a middle flange value of 2. I use the square (also called a pulse) wave table by specifying a value of 3.

I accepted the default setting values and clicked the OK button to generate the Cluster Bass data track (see Figure 11-15). Click the play button to preview the sample.

Next, let’s take a look at the harmonic noise generator.

The harmonic noise generator allows you to set a MIDI Note List and the Number of Harmonics to generate from this list. There are also Duration, Band Width, and Odd Harmonics Only options in the Harmonic Noise dialog (see Figure 11-16) to generate a very unique noise track.

I accepted the default setting values and clicked the OK button, generating the Harmonic Noise sample data track seen in Figure 11-17. Click the play button to preview the Harmonic Noise stereo sample, which you’ll see (and hear) is out-of-this-world extraterrestrial in nature. The waveforms even look like alien centipedes—and they sound even stranger than they look!

Next, let’s return to an audio tone generator that comes preinstalled in Audacity 2.1—the Pluck tone generator. No, not the Cluster Pluck generator; let’s keep it clean here. It’s just a simple pluck-string instrument generator that can be used to simulate bass guitars, guitars, or even banjos, using the proper digital audio effects processing.

The Pluck tone generator is much simpler than the other audio synthesis algorithms you’ve seen in this chapter. It allows you to set Pluck MIDI Pitch, which defaults to middle C, as well as Fade-out type, which I set to gradual, because it’s more like what a plucked string does in real life. There is also Duration in seconds, which I set to 1.00 second. You can see these options in the Pluck dialog shown in Figure 11-18.

I accepted the default setting values and clicked the OK button, generating the Pluck sample data track shown in Figure 11-19. Click the play button to preview the Pluck stereo sample. I noticed a high level at the beginning of the sample, so I took a screenshot of the playback to show this.

This is most likely because a plucked string generates a high decibel level right after the string is released, generating all o f its audio “power,” or its amplitude, at that initial point in time.

These Generate menu digital audio synthesizers, or waveform generation algorithms, bring a lot of power to your digital audio editing and compositing work process.

If you think “outside of the box” and utilize Audacity’s vast Effect menu in conjunction with the Analyze menu, you will be able to create any digital audio assets that you need fo r your multimedia projects.