Audacity - Audacity is a free and open-source audio production software suite that includes a surprising array of editing tools and recording systems.
Adobe Audition - Mix, edit, and create audio content in Adobe Audition CC with a comprehensive toolset that includes multitrack, waveform, and spectral display.
Noise Destroyer - Remove Backround Noise From Audio or Video
Oceanaudio - Ocenaudio is a cross-platform, easy to use, fast and functional audio editor.
DarkAudacity - DarkAudacity is a build/fork of Audacity with quote "a darker more modern theme - and a few small tweaks."
Tenacity - Tenacity is an easy-to-use, privacy-friendly, FLOSS, cross-platform multi-track audio editor/recorder for Windows, macOS, Linux and other operating systems.