advice on improving quality of low-bit recordings


I have some old audiobooks that got digitized from cassette at 16 kbps and 11.025 kHz. Needless to say the quality isn’t so good (lots of that glittery-sounding distortion especially). I’m hoping to get some advice on what features/processes in Audacity might be best for trying to gain some improvement. Beyond Noise Removal I’m very novice at the techniques. I expect there’s only so much to be done, but any advice much appreciated. I also assume that just creating a new version (e.g., through iTunes) at higher rates will not solve my problem.

I am using OS X Mavericks, Audacity 2.0.5. (I also use most recent Audacity on the most recent version of Windows, but I assume any solutions would apply to either system.)

Thank you all very much!


Probably not. Opening the work in a very high quality just means the work won’t get any worse. If it’s straight speech, there are exotic rescues like speech to text converters and then text to speech. But if the original is ratty, then they might not work so well, either.

You may have well asked :

"I have a > thumbnail-image > of a > screen-grab > …
thumbnail sized screengrab of this page.png
how do I recreate a full-screen version from this thumbnail image, where all the text is readable ? " [/i]

The answer is it can’t be done : information was lost in the conversion [and processing artifacts were added].

This is not an Audacity-specific limitation : lossy compression cannot be undone.

[ Experimenting with the equalization may produce some subjective improvement in your audiobooks …

Audacity Manual ]

Good analogy.