AthTek Free Voice Changer is a handy audio tool for Windows users. It has a very clean interface without any exaggerated color and overstated features. It clearly lists 4 steps for you to obtain the sound effects you want.
Audio Amplifier Free boots the actual volume of audio file or video file. This cute freeware will amplify or increase the sound of a video file without changing the video quality. It supports all popular video and audio formats.