AcouFiend from Blue Cat Audio is an acoustic feedback simulator plug-in that can make your guitars scream, growl or sing, even at low volume or through headphones. AcouFiend simulates the acoustic feedback (a.k.a "Larsen effect") well known to guitarists playing loud and close to their speaker, except that here, you have total control over the effect. You can choose when and how to trigger the feedback on sustained notes or chords. The plug-in lets you select the main harmonic of the feedback, and you can even choose to transpose it for more creative effects. This versatile plug-in is great for shaping guitar tone, creating screaming synths and sustained vocal harmonies and much more.