Adjust the delay correctly:

  • 50-60ms for normal speaking rates.
  • 60-80 ms for “slow normal” speaking rates.
  • 100ms or longer should only be used with fluency shaping therapy (slow, prolonged speech).

Try a better DAF device. Some DAF devices and phone apps sound awful.

Combine FAF with DAF. FAF pitch shifts around -0.5 octaves (a half octave down) are effective and sound good.

Use a better microphone. The microphone should be close to your mouth or contacting your throat. It should be noise-canceling and not pick up background noise.

Use better earphones. Adult male vocal folds vibrate around 125 Hz. FAF lowers that below 100 Hz. SpeechEasy devices have a frequency range of 200-8,000 Hz, with a peak response around 3,000 Hz. DAF doesn’t work if you can’t hear your voice.

Combine fluency shaping therapy with DAF. Slow down by stretching your vowels.