Maybe a slightly unusual question: If I have a long recording of about a few hours and I create several smaller ones from this recording by cutting out fragments and re-saving, will the quality of these recordings not change through such actions?
No the quality should not change.
I frequently cut 3 min. or so songs out of 2 hour webcasts and the quality is fine.
You can loose quality when editing MP3 or other lossy formats. WAV or an Audacity project can be edited losslessly. So if you are digitizing cassettes or vinyl and you want to make MP3s, do all of your editing in a lossless format and make the MP3 as the last step.
MP3 is lossy compression and data is thrown away to make the file smaller. (It can still often sound identical to the original.) When you open an MP3 in Audacity (or any “regular” audio editor) it gets decompressed. If you then export as MP3 you are going through another generation of lossy compression and there is some accumulated damage.
If you are stuck with MP3 originals there are some special-purpose MP3 editors (like mp3DirectCut) that can do limited editing without decoding. Otherwise, you can export as a lossless format to avoid any additional damage, or just try to minimize the number of times it’s re-compressed.
These are recordings from the scanner, which I save as Audacity Project File (.aup). They last several hours, and I’m usually only interested in one or a few short fragments of the recording. Normally, I edit such a recording and export it as a FLAC file. Unfortunately, I can’t keep up with the exact processing of the recordings and these few hours of movies fill my hard drive. So I’m looking for a solution, can I easily re-save such an .aup file into several smaller ones (leaving only what interests me) without worrying about any losses. Ultimately, I will edit and export these re-saved fragments as FLAC anyway.