# Index of Effects, Generators and Analyzers

### From Audacity Manual

This page is a quick index to the Effects, Generators and Analyzers shipped with Audacity. You may also add new plug-ins in various popular formats.

- An Effect changes the audio in some way.
- A Generator creates new audio, either in an existing track or in a new track.
- An Analyze tool performs analysis on a selection of audio - it does not change the audio and does not create new audio.

Although by default, no keyboard shortcuts are provided for most Effect, Generate or Analyze commands, it is possible to set up your own shortcut for any of these commands. For instructions on how to do this please see Keyboard Preferences.

| When playing, recording or paused, the Effect menu will appear grayed out, because changes to the audio data cannot be made until you press the yellow Stop button .

## Alphabetical Index of Effects, Generators and Analyzers

Adjustable Fade Compressor High Pass Filter Pluck Sound Finder
Amplify Contrast Invert Regular Interval Labels Studio Fade Out
Auto Duck Cross Fade In Leveler Repair Tone
Bass and Treble Cross Fade Out Low Pass Filter Repeat Tremolo
Beat Finder Delay Noise Reverb Truncate Silence
Change Pitch DTMF Tones Noise Removal Reverse Vocal Remover
Change Speed Echo Normalize Risset Drum Vocoder
Change Tempo Equalization Notch Filter Sample Data Export Wahwah
Chirp Fade In Nyquist Prompt SC4
Click Removal Fade Out Paulstretch Silence
Click Track Find Clipping Phaser Silence Finder
Clip Fix Hard Limiter Plot Spectrum Sliding Time Scale / Pitch Shift

Where an effect, generator or analyzer has settings, its description page (accessed by the links below) shows an image of the interface and its default settings.

## Effects by Function

### Make the sound louder or quieter

- Amplify: This effect increases or decreases the volume of the audio you have selected.
- Auto Duck: Reduces (ducks) the volume of one or more tracks whenever the volume of a specified "control" track reaches a particular level. Typically used to make a music track softer whenever speech in a commentary track is heard.
- Compressor: Compresses the dynamic range by two alternative methods. The default "RMS" method makes the louder parts softer, but leaves the quieter audio alone. The alternative "peaks" method makes the entire audio louder, but amplifies the louder parts less than the quieter parts. Make-up gain can be applied to either method, making the result as loud as possible without clipping, but not changing the dynamic range further.
- Hard Limiter: An extreme Compressor effect. It can sometimes be used to remove stubborn clicks.
- Leveler: This effect makes quiet passages louder and loud passages quieter. It does this in a way that is different from the Compressor effect. As a result it does add some distortion to the processed audio. The only way to be sure if the effect does what you want is to try it. For example, applying this effect twice at its Heaviest setting on a normally-recorded voice can produce an "air traffic controller" effect.
- Normalize: Use the Normalize effect to set the maximum amplitude of a track, equalize the amplitudes of the left and right channels of a stereo track and optionally remove any DC offset from the track.
- SC4: This effect is a stereo compressor with a variable envelope follower for RMS / peak behavior.

### Fade a section in or fade it out

- Cross Fade In: Despite the name this effect does not do an automatic cross fade between two tracks or clips. This fade applies a curve that will result in equal volume throughout the fade once the faded in and faded out regions are mixed.
- Cross Fade Out: This fade applies a curve that will result in equal volume throughout the fade once the faded in and faded out regions are mixed.
- Fade In: Applies a linear fade-in to the selected audio - the rapidity of the fade-in depends entirely on the length of the selection it is applied to. For a more customizable logarithmic fade, use the Envelope Tool on the Tools Toolbar.
- Fade Out: Applies a linear fade-out to the selected audio - the rapidity of the fade-out depends entirely on the length of the selection it is applied to. For a more customizable logarithmic fade, use the Envelope Tool on the Tools Toolbar.
- Studio Fade Out: Applies a more musical fade out to the selected audio, giving a more pleasing sounding result.
- Adjustable Fade: enables you to control the shape of the fade (non-linear fading) to be applied by adjusting various parameters; allows partial (that is not from or to zero) fades up or down.

For a discussion of what the different types of fade do, see Fades

### Change the quality of the sound

- Bass and Treble...: Increases or decreases the lower frequencies and higher frequencies of your audio independently; behaves just like the bass and treble controls on a stereo system.
- Equalization: Adjusts the volume levels of particular frequencies.
- High Pass Filter...: Passes frequencies above its cutoff frequency and attenuates frequencies below its cutoff frequency.
- Low Pass Filter...: Passes frequencies below its cutoff frequency and attenuates frequencies above its cutoff frequency.
- Paulstretch: Use Paulstretch only for an extreme time-stretch or "stasis" effect, This may be useful for synthesizer pad sounds, identifying performance glitches or just creating interesting aural textures. Use Change Tempo or Sliding Time Scale rather than Paulstretch for tasks like slowing down a song to a "practice" tempo.
- Phaser: The name "Phaser" comes from "Phase Shifter", because it works by combining phase-shifted signals with the original signal. The movement of the phase-shifted signals is controlled using a Low Frequency Oscillator (LFO).
- Tremolo: Modulates the volume of the selection at the depth and rate selected in the dialog. The same as the tremolo effect familiar to guitar and keyboard players.
- Vocoder: Synthesizes audio (usually a voice) in the left channel of a stereo track with a carrier wave (typically white noise) in the right channel to produce a modified version of the left channel. Vocoding a normal voice with white noise will produce a robot-like voice for special effects.
- Wahwah: Rapid tone quality variations, like that guitar sound so popular in the 1970's.

### Repair damaged audio

- Click Removal: Click Removal is designed to remove individual clicks on audio tracks and is especially suited to declicking recordings made from vinyl records, without damaging the rest of the audio.
- Clip Fix: Clip Fix attempts to reconstruct clipped regions by interpolating the lost signal.
- Noise Removal: This effect is ideal for removing constant background noise such as fans, tape noise, or hums. It will not work very well for removing talking or music in the background. More details here.
- Notch Filter: Greatly attenuate ("notch out") a narrow frequency band. This is a good way to remove mains hum or a whistle confined to a specific frequency with minimal damage to the remainder of the audio.
- Repair: Fix one particular short click, pop or other glitch no more than 128 samples long.

### Make the sound faster, slower, lower pitched or higher pitched

- Change Pitch: Change the pitch of a track without changing its tempo.
- Change Speed: Change the speed of a track, also changing its pitch.
- Change Tempo: Change the tempo of a selection without changing its pitch.
- Sliding Time Scale / Pitch Shift: This effect allows you to make a continuous change to the tempo and/or pitch of a selection by choosing initial and/or final change values.
- Paulstretch: Use Paulstretch only for an extreme time-stretch or "stasis" effect, This may be useful for synthesizer pad sounds, identifying performance glitches or just creating interesting aural textures. Use Change Tempo or Sliding Time Scale rather than Paulstretch for tasks like slowing down a song to a "practice" tempo.
- Truncate Silence: Automatically try to find and eliminate audible silences. Don't use with faded audio.

### Add reverberation or echo

- Delay: A configurable delay effect with variable delay time and pitch shifting of the delays.
- Echo: Repeats the selected audio again and again, normally softer each time and normally not blended into the original sound until some time after it starts. The delay time between each repeat is fixed, with no pause in between each repeat. For a more configurable echo effect with a variable delay time and pitch-changed echoes, see Delay.
- Reverb: A configurable stereo reverberation effect with built-in and user-added presets. It can be used to add ambience (an impression of the space in which a sound occurs) to a mono sound. Also use it to increase reverberation in stereo audio that sounds too "dry" or "close".

For details of the underlying principles of delay and reverb effects please see this page in the Wiki.

### Remove vocals

- Invert: This effect flips the audio samples upside-down. This normally does not affect the sound of the audio at all. It is occasionally useful for vocal removal.
- Vocal Remover: Attempts to remove center-panned vocals from a stereo track. Help text is available from within the dialog.

### Manipulate Audio

- Repeat... repeats the selection the specified number of times.
- Reverse reverses the selected audio; after the effect the end of the audio will be heard first and the beginning last.

### Invoke Nyquist

- Nyquist Prompt... brings up a dialog where you can enter Nyquist commands. Nyquist is a programming language for generating, processing and analyzing audio. For more information see Nyquist Plug-ins Reference.

## Generators by Function

### Generate Tones

- Chirp: Generates four different types of tone waveform like the Tone Generator, but additionally allows setting of the starting and ending amplitude and frequency.
- DTMF Tones: Generates dual-tone multi-frequency (DTMF) tones like those produced by the keypad on telephones.
- Tone: Generates 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.

### Generate Silence or Noise

- Noise: Generates 'white', 'pink' or 'brown' noise.
- Silence: Creates audio of zero amplitude, the only configurable setting being duration.

### Generate Instruments or Metronome

- Click Track: Generates a track with regularly spaced sounds at a specified tempo and number of beats per measure (bar).
- 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.

## Analyzers by Function

### Analyze Amplitude or Other Audio Properties

- Contrast: Analyzes a single mono or stereo speech track to determine the average rms difference in volume (contrast) between foreground speech and background music, audience noise or similar. The purpose is to determine if the speech will be intelligible to the hard of hearing.
- Find Clipping: This displays runs of clipped samples in a Label Track, as a screen-reader accessible alternative to View > Show Clipping. A run must include at least one clipped sample, but may include unclipped samples too.
- Plot Spectrum: This takes the selected audio (which is a set of sound pressure values at points in time) and converts it to a graph of frequencies against amplitudes.
- Sample Data Export: This reads the values of successive samples from the selected audio and prints this data to a plain text, CSV or HTML file. Further information may be added as a "header" at the top of the file.

### Divide Up Sounds or Silences using Labels

- Regular Interval Labels: Places labels in a long track so as to divide it into smaller, equally sized segments.
- Silence Finder: Divides a track up by placing point labels inside areas of silence.
- Sound Finder: Divides a track up by placing region labels for areas of sound that are separated by silence.

### Mark Beats using Labels

- Beat Finder: Attempts to place labels at beats which are much louder than the surrounding audio. It's a fairly rough and ready tool, and won't necessarily work well on a typical modern pop music track with compressed dynamic range. If you don't get enough beats detected, try reducing the "Threshold Percentage" setting.

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