Audacity is shipped with many effects that you can use to modify your audio.

• Real-time preview of LADSPA, LV2, VST and Audio Unit (macOS) effects.
• Plug-in Manager handles plug-in installation and addition/removal of effects and generators from the menus.
• Generate tones, silence, noise, instruments or rhythm track.
• Change the pitch without altering the tempo.
• Change the tempo without altering the pitch.
• Noise Reduction to remove static, hiss, hum or other constant background noises.
• Alter frequencies with Equalization, Bass and Treble, High-Pass, Low-Pass and Notch Filter effects.
• Filter a frequency selection created in Spectrogram view or Spectral Selection Toolbar using spectral edit effects.
• Adjust volume with Compressor, Amplify, Normalize, Fade In/Out, Studio Fade Out, Crossfade Clips, Crossfade Tracks and Adjustable Fade effects.
• Reduce or Isolate Vocals given suitable stereo tracks (vocal reduction produces a stereo result).
• Create voice-overs for podcasts or DJ sets using Auto Duck effect.
• Other built-in effects include:
  • Distortion
  • Echo
  • Limiter
  • Paulstretch (extreme stretch)
  • Phaser
  • Reverb
  • Reverse
  • Truncate Silence
  • Wahwah
• Run chains of effects on a project or multiple files usimg  Macros.