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
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
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
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.
Click Removal - This effect is designed to remove the annoying clicks
on recordings from vinyl records without damaging the rest of the audio.
You can choose how sensitive the click detection is, and what the maximum
length of a click is.
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
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
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
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.