# Generate Menu

### From Audacity Manual

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 in a selection to replace that selection with the new 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 how to do this please see Keyboard Preferences.

## Usage

- To generate into a new track: If there are no existing tracks, choose the required generator. If there are existing tracks, click outside the tracks in the gray background to deselect them, then Generate. To deselect tracks using the keyboard, press <enter>, then to deselect any further tracks, use up or down arrow and <enter> as needed.
- To insert generated audio at the cursor position: Place the cursor in the track, then Generate. The specified duration of audio will be inserted into the selected tracks at the cursor position, thus extending the length of the selected track(s).
- To replace an existing selection with generated audio: Select the region, then Generate. The selected region(s) will be replaced with the generated audio. The total length of the selected tracks will remain the same, unless you change the length in the generator to replace the selection with a longer or shorter one. You can select an exact region to replace using Selection Toolbar.

Having placed the cursor or selected the region, there are several ways to select extra tracks so as to generate into those at the same time. The simplest method is to hold down SHIFT then use up or down arrow on the keyboard. See Audacity Selection for more details.
Duration and Selection Format: Type (or use the keyboard arrows) to enter the required Duration. If the first digit you want is highlighted, just type the whole number. If the required first digit is not highlighted, you can use left or right arrow on your keyboard to move to the first digit, then type. You can also increment a highlighted digit with keyboard up or down arrow instead of typing.

If there is no audio selection, Duration defaults to 30 whole seconds, but the last entered whole seconds Duration is then always remembered. If there is selected audio, the generator always displays the exact duration of that selection to the nearest audio sample, as in the images below. To change the Selection Format to another unit of Duration so that the generation will be in those units, hover over or select in the Duration digits, then right-click or use the Context key. Alternatively, click the downward-pointing arrow to right of the digits.

Amplitude: All generators (except of course Silence) let you type in an amplitude value to set the loudness of the generated audio. Permitted values are between 0 (silence) and 1 (the maximum possible volume without clipping), with a default of 0.8.

See the examples below for a couple of common audio generation scenarios.

## Built-in Generators

### Chirp...

Produces four different types of tone waveform like the Tone Generator, but additionally allows setting of the starting and ending amplitude and frequency. Short tones can thus 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, as 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 type 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.

### Tone...

Choose amplitude, one of four different tone waveforms: Sine, Square, Sawtooth or Square (no alias), 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.

Note: Nyquist generators do not take the length of any selected audio as the length of the audio to be generated: 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, but the total length of the track(s) will change unless the selected and specified lengths are identical.

### 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. To do this, enable "Play other tracks while recording new one" in the Recording Preferences. Any length of track can be created by adjusting "number of measures" accordingly, and the type and pitch of the sound can be customized. Once created, the track can be edited (for example, its volume changed) like any audio track. Note: When exporting your finished recording, use the Track Control Panel to either close or mute the Click Track, so that it's not audible in the recording.

### 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. The length of the drum sound is determined by the "Decay" field.

## Examples

Example 1: Insert two seconds of silence at the start of the track as a "lead-in".

1. Click the "Skip to Start" button or press HOME to place the cursor at the start of the track.
2. Choose Silence from the Generate Menu.
3. Specify the two seconds silence. This works by the highlighted digit being overtyped with the figure you enter, then the highlight moving to the next digit. So if the value is showing at 30 seconds with "3" highlighted, simply type "02". To change the digit that is highlighted, click on the one you want to highlight or use the left or right arrow keys on your keyboard.
4. Click OK or hit ENTER on your keyboard.

Example 2: Replace a 30 second section of audio starting at 1 minute 15 seconds with a tone.

1. Click in the track at 1 minute 15 seconds (underneath "1:15" in the Timeline above the track).
2. Drag your mouse to the right to select 30 seconds of audio, then release the mouse button.
3. Choose Tone from the Generate menu.
4. Specify your Waveform, Frequency and Amplitude in the dialog
5. Click OK or hit ENTER on your keyboard.

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