Why do I hear random high notes occasionally from my synth?
These are known as “ghost notes” or “false triggers”. They are caused by harmonics that may sound more like overtones or noise in your normal guitar tones. You can adjust the sensitivity of most guitar-to-midi converters on a string by string basis. Lowering the sensitivity may cause the tracking to be less accurate or soft notes may not be triggered at all. The real cause of these harmonics is technique. Raking across several strings, muting incorrectly with either hand, touching strings unintentionally can all cause ghost notes.