Change Tempo: changes the tempo (pace) of the audio, without changing the pitch.
Obviously, this changes the length of the selection.
Compressor: compresses the dynamic range of the selection. Loud parts will be
softer while keeping the volume of the soft parts the same. You can optionally
normalize the recording afterwards, resulting in the entire piece having a higher
perceived volume.
Echo: this very simple effect repeats the selection with a descending sound, like a
series of echoes. 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: boosts or reduces random frequencies. You can select one of a
number of different curves designed to equalize the sound of some popular record
manufacturers, 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 random frequencies.
The curve uses a linear scale for frequency.
Invert: vertically flips the waveform, just as a phase inversion in the analogue domain.
Noise Removal: cleans up any 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, and re-select
"noise removal". Now click on 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: corrects the DC offset (a vertical displacement of the track) and/or
amplifies a track as such, that the maximum amplitude is a fixed amount: -3 dB. It is
useful to normalize all your tracks before mixing. If you have many tracks, you may
need to use the track's gain sliders to turn some down.
Nyquist Prompt: this is for advanced users only! This function allows you to
express random transformations, 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 combines phase-
shifted signals with the original signal. Move the phase-shifted signals by 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.
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