Generate Menu

Peter 10Dec12: I have moved the long discussion ednotes to the Talk page.

• ToDo ready for editorial review and merciless editing.
• ToDo I do wonder if we should move the Usage&Examples section up to the top before the "Built-in Generators", I think I'd prefer it there - thoughts?
  • Ed 10 December 2012I would move it to the top.
    • Peter 10Dec12: Done - I moved it to the top - much better there imo.

The items in the Generate menu create new audio containing tones, noise or silence. Generate at a cursor position to insert the new audio and extend the track or with a selection to replace that selection with the newly generated audio. Although, by default, no keyboard shortcuts are provided for the generators, it is possible to set up your own shortcut for any Generate command; for instructions on this please see Keyboard Preferences.

Usage and Examples

See this page in the manual for a help with the usage of the Audacity generators and how to:

• generate audio into a new track,
• insert generated audio at the cursor position,
• replace an existing selection with generated audio.

Built-in Generators

Chirp...

Produces four different types of tones like the Tone Generator but additionally allows setting of the start and end amplitude and frequency. Short tones can be made to sound very much like a bird-call. As with Tone, frequencies can be specified anywhere between 1 Hz and half the current project rate shown in the Selection Toolbar.

DTMF Tones...

Generates dual-tone multi-frequency (DTMF) tones like those produced by the keypad on telephones. Enter numbers from 0 to 9, lower case letters from a to z, and the * and # characters. You can also enter the four "priority" tones used by the US Military (upper case A, B, C and D). As with most of the generators you can choose the amplitude and overall duration of the sequence. Use the slider to select the ratio between the length of each tone in the series and the length of the silences between them. This ratio is displayed underneath the slider as the "duty cycle" along with the resulting duration of each tone and silence. For example, if you create four tones in a sequence lasting four seconds, with a duty cycle of 50%, the four tones and the three silences between them will all be the same length (571 milliseconds).

Noise...

Choose amplitude and one of three different "colors" of noise. White noise is that which has the greatest ability to mask other sounds, as it has similar energy at all frequency levels. Pink noise and brown noise both have more energy at lower frequencies, especially brown noise, which has the most muffled, low pitched sound of the three types.

Silence...

Creates audio of zero amplitude, the only configurable setting being duration. When applied to an audio selection, the result is identical to Edit > Remove Audio > Silence Audio.

Steve 15Nov12: Is the default "units" for "Generate > Silence" hh:mm:ss_milliseconds? The image shows hh:mm:ss+samples.

• Peter 15Nov12: Certainly the other examples shown on this page use hh:mm:ss_milliseconds for their units.
• Gale15Nov12: You are not RTFM :=) "If there is selected audio, the generator always displays the exact duration of that selection to the nearest audio sample, as in the Silence Generator image below." I've tried putting that in a note div now. This information is also in the image hover text.
• Steve 11Dec12: Even with the hover text, it strikes me as odd and inconsistent that the other generators show default settings when there is no selection, and the hover text says "Noise generator dialogue", "DTMF Tone generator dialogue" and so on rather than a full sentence explaining what action is being performed.

Tone...

Choose one of four different tone waveforms: Sine, Square, Sawtooth or Square (no alias), set amplitude and a frequency between 1 Hz and half the current project rate (as shown in the Selection Toolbar). One half is chosen because a given sample rate can only carry frequencies up to half that rate. Although frequencies above 20000 Hz cannot be heard by most humans, generating at up to half the sample rate (22050 Hz at Audacity's default 44100 Hz) can have scientific uses, for example in measuring impulse responses. Note that creating tones at or close to half a given sample rate may (correctly) generate either silence or a pulsing rather than steady tone, according to the type of waveform chosen.

Plug-in Generators

Any additional generators which appear underneath the menu divider are Nyquist or LADSPA plug-ins. Audacity includes the following three Nyquist generators, but more are available on Download Nyquist Plug-ins on our Wiki.

Nyquist generators do not take the length of any selected audio as the length of the audio to be generated. Instead, specify the length required in the appropriate input field(s) of the plug-in. Any selected audio will be replaced by the length of audio specified in the plug-in, thus the total length of the track(s) will change unless the selected and specified lengths are identical.

Ed 10Dec12: In re: "do not take the length of any selected audio…" what is the situation with LADSPA?

• Steve 11Dec12: On Linux, LADSPA generate plug-ins generally have a duration slider that is set by default to the current selection length or to 30 seconds if there is no selection. However, if there is a selection, then most LADSPA generators fail and produce nothing or cause Audacity to crash.

Ed 10Dec12: In the descriptions of the following three Generators we follow the section titles (Click Track…, Plucky… & Risset Drum…) with a sentence fragment whose first word is capitalized. I feel uncomfortable with the sentence fragments.

Click Track...

Generates a track with regularly spaced sounds at a specified tempo and number of beats per measure (bar). This can be used like a metronome for setting a pulse to record against.

Pluck...

A synthesized pluck tone with abrupt or gradual fade-out, and selectable pitch corresponding to a MIDI note.

Risset Drum...

Produces a realistic drum sound consisting of a sine wave ring-modulated by narrow band noise, an enharmonic tone and a relatively strong sine wave at the fundamental.