Audacity - Audacity is a free and open-source audio production software suite that includes a surprising array of editing tools and recording systems.
Acoustica - Acoustica is an audio editing tool for editing, mastering and restoration work on both Mac and PC.
GarageBand - GarageBand is a fully equipped music creation studio for Mac
iZotope RX6 - iZotope RX6 is a noise reduction and audio repair software.
Adobe Audition - Mix, edit, and create audio content in Adobe Audition CC with a comprehensive toolset that includes multitrack, waveform, and spectral display.
AVS Audio Editor - AVS Audio Editor enables user to apply various effects and filters like cut, join, trim, mix, delete parts, split audio files.