A free program for Android, by StereoMatch.

Voice Changer for Gaming PC PS4 XBox 2ndPhone is an app for the Android platform. It is a high-quality voice changer, and it can record your voice, make it sound like another person, and change the pitch. You can use this app with your Android device, PC, or PS4. It is compatible with both Android phones and controllers. You can use it with other devices, but you cannot use it with the same device (i.e. the app cannot record and change the sound on the same device).