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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 “ Allow
clipping” checkbox, it will let you amplify so much that the audio ends up
beyond the range of the waveform, and is clipped (distorted). The default
value when you open the effect is to amplify so that the loudest part of the
selection is as loud as possible without distortion.
Bass Boost –
enhances the bass frequencies in the audio.
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 soft parts the same. You can optionally normalise the recording
afterwards, 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 echo’s. 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).
