At first I should admit I have very limited knowledge about sounds and working with them.

I have hundreds of old files, low quality recorded lectures, most probably recorded on cassette.

Is there any way for me to improve the quality and make the speech more clear? After that I have to make it louder too.

I have used "Noise Reduction" of Audacity and managed to remove the basic noise, but the speech quality is yet unacceptable. Here is 10 seconds of files, before applying any filters:


Thank you in advance

1 Answer 1


This is not my specialist area & this software is not my usual sound tool, but this is the kind of task that Izotope RX is designed for. It's not cheap. I only have RX 7 not the latest, so some areas may have been improved since my version. There's a 30-day free trial so you can give it some time to see if it's what you need. I very much doubt you will get even half as close with anything freeware.

I ran it through De-Clip, EQ, Dialogue De-reverb, Dialogue Isolate & Leveller.
Somebody better at this may drag some more intelligibility out of it, but this was the best I can manage.

enter image description here

End result, not great tbh. I don't know if it's truly intelligible as I have no idea even what the language is, let alone what it's saying ;)

Tweaked version


Original, for quick comparison


  • 1
    Thank you. The Whole procedure you described was interesting to me. The voice of lecturer is changed but it is more clear.
    – mohsenof
    Commented Nov 20, 2020 at 4:00
  • @mohsenof - while Tetsujin is correct in pointing out that this is pretty much the only partial solution for the problem. In reality, the only full solution for bad audio is to re-record it, as you cannot create information that was already lost with a bad recording.
    – Rory Alsop
    Commented Nov 26, 2020 at 9:59

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