Wave Corrector is a freeware program that analyzes your audio files, and correct several noise issues. For vinyl, it can greatly reduce the clicks and pops from 78s, as an example. It also contains rumble and other filters that can improve the audio.
Although I haven't tried the feature, it's also supposed to reduce the hiss from cassette tapes.
One of the neat features is that it lists in a table all the click corrections it has made; you can individually go through each, see the original waveform and the 'fixed' one, and make manual changes if you desire.
I found for really worn and noisy records, with loud clicks, it made a big difference. For others, not as much; it can't get rid of general surface noise without taking too much away from the actual audio that it's buried within.
I plan on using it for problematic audio, where the noise really affects the overall listening experience. I found it more effective than Audacity's noise removal, which does tend to affect the original audio.
I haven't checked it out yet but it reminds me of a software called CapCap. There's a guy on YouTube that features "restored" Quiet Please episodes which are really incredibly better sounding compared to their poor quality originals. I had asked him how he accomplished that and he said he mostly used CapCap.
It's free software for pc and Mac and has a great reputation. https://www.capcut.com/resource/audio-editor-free-download
Just now I notice they also have an online version of it: https://www.capcut.com/tools/online-audio-editor.
I haven't personally tried either, in fact I forgot about it until you brought this subject up
https://www.capcut.com/resource/top-6-ai-audio-restoration-tools-for-historical-audio
CapCut utilizes AI-driven tools for restoring low-quality audio and video content. Key audio features include Enhance Voice for separating speech from noise, Noise Reduction for static, and Voice Isolation to prioritize dialogue. Visual tools include AI Video Upscaler for increasing resolution, Old Photo Restoration, and Flicker Remover for old footage inconsistencies.
Wave Corrector is a freeware program that analyzes your audio files, and correct several noise issues. .....
I just checked it out, appears pretty impressive. For some reason I thought you were talking about an online audio editor - not sure how I got that idea, must have been looking at something else!
Anyway that Wave Corrector software looks pretty cool, definitely worth playing around with. But really I doubt there's anything that Audacity can't do. - but Wave Corrector apparently streamlines it for restoring poor audio. I've spent hours and hours before manually removing click by click!
Just of note, in their FAQ:
Not directly. Because of licensing restrictions we do not support MP3. However, Wave Corrector does support the open source equivalent of MP3 called Ogg Vorbis. ...
The software has apparently been out a long time and he's obviously not going to be developing Wave Corrector further now that he's made the previously paid Professional version freeware, but it's worth noting that MP3 files have been free from any and all patent restrictions since 2017
Yeah, they don't support mp3. But then, Audacity converts mp3 to wave, does all it's manipulation and then converts back. It's also pretty easy to do with ffmpeg.
I've done the click removal manually with Audacity as well, but you do end up snipping bits and pieces of the audio. Not noticeable as long as your're careful, but Wave Corrector actually smooths the audio out, leaving everything else intact. The clicks are still there in the background, but not nearly as noticeable, and overall I feel it's a much better solution.
The noise removal functions in Audacity do affect the remaining audio. I've found they decrease the treble quite a bit.
When I manually removed clicks I didn't just cut each click out, - I filled the click in - with a copy of an adjacent "clean" fraction of the file not having a click, that way all those miniscule sections removed don't accumulate and alter the time stamps of the file at all.
I've not been satisfied by any automated click removal I've used (not even with the premium software restorers), at least not with badly damaged audio like the Quiet Please episodes.
Don't care much for any of the noise removable functions either, not in Audacity nor in higher end software like iZotope (although iZotope is more effective than Audacity, but they both screw up the "sonics" of the audio when cleaning) - I had done excessive experimentations with the Quiet Please episodes years ago and noticably improved several episodes, but the ones that guy cleaned on YouTube with CapCap software are generally better with apparently less effort.
Combined use of auto and manual cleaning is the best way to go about it