Audacity - Effect Menu

# Effect Menu

The items in this menu only work when you have audio selected. Audacity does not have any real-time effects; you must select the audio, apply the effect, and then listen to the results.

Most effects have a Preview button. Clicking on this button plays up to three seconds of audio, allowing you to hear what it will sound like after the effect is applied. This is useful for fine-tuning the effect parameters.

Repeat Last Effect - selecting this command is a shortcut to applying the most recent effect with the same settings. This is a convenient way to quickly apply the same effect to many different parts of a file.

Amplify - changes the volume of the selected audio. If you click the "Don't allow clipping" checkbox, it won't let you amplify so much that the audio ends up beyond the range of the waveform.

BassBoost - enhances the bass frequencies

Change Pitch - changes the pitch/frequency of the selected audio without changing the tempo. When you open the dialog, the starting frequency is set to Audacity's best guess as to the frequency of the selection. This works well for recordings of singing or musical instruments without background noise. You can specify the pitch change in one of four different ways: musical note, semitones, frequency, or percent change.

Change Speed - changes the speed of the audio by resampling. Making the speed higher will also increase the pitch, and vice versa. This will change the length of the selection.

Change Tempo - changes the tempo (speed) of the audio without changing the pitch. This will change the length of the selection.

Compressor - compresses the dynamic range of the selection so that the loud parts are softer while keeping the volume of the soft parts the same. You can optionally apply gain, resulting in the entire piece having higher perceived volume.

Echo - very simple effect that repeats the selection with a decay, sounding like a series of echos. This effect does not change the length of the selection, so you may want to add silence to the end of the track before applying it (using the Generate Menu).

Equalization - Boost or reduce arbitrary frequencies. You can select one of a number of different curves designed to equalize the sound of some popular record players, or draw your own curve.

Fade In - fades the selection in linearly

Fade Out - fades the selection out linearly

FFT Filter - similar to Equalization, lets you enhance or reduce arbitrary frequencies. The curve here uses a linear scale for frequency.

Invert - Flips the waveform vertically, reversing its phase.

Noise Removal - This effect lets you clean up noise from a recording. First, select a small piece of audio that is silent except for the noise, select "Noise Removal", and click on the "Get Noise Profile" button. Then select all of the audio you want filtered select "Noise Removal" again, and click the "Remove Noise" button. You can experiment with the slider to try to remove more or less noise. It is normal for Noise Removal to result in some distortion. It works best when the audio signal is much louder than the noise.

Normalize - allows you to correct for DC offset (a vertical displacement of the track) and/or amplify such that the maximum amplitude is a fixed amount, -3 dB. It's useful to normalize all of your tracks before mixing.

Nyquist Prompt - for advanced users only. Allows you to express arbitrary transormations using a powerful functional programming language. See the Nyquist section of the Audacity website for more information.

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).

Repeat - repeats the selection a certain number of times. This operation is quite fast and space-efficient, so it is practical to use it to create nearly-infinite loops.

Reverse - This effect reverses the selected audio temporally; after the effect the end of the audio will be heard first and the beginning last.

Wahwah - uses a moving bandpass filter to create its sound. A low frequency oscillator (LFO) is used to control the movement of the filter throughout the frequency spectrum. Adjusts the phase of the left and right channels when given a stereo selection, so that the effect seems to travel across the speakers.

Any items which appear after these built-in effects are VST, Ladspa, or Nyquist plug-ins. It is possible for a poorly written plug-in to crash Audacity, so always save your work before using a plug-in effect.