Hello everybody, I’m looking for a way to tell “Change tempo” or “Sliding Time Scale…” effects how to modify a piece of audio.
I did some tests slowing down the same file to a similar (very low) speed (0.30 the original speed), keeping the original pitch, and here’s what I got:
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Audacity’s “Change Tempo” effect: there’s a lot of reverb-like side effect, because (I guess) the micro-parts of the original audio that are repeated to fill the longer time range are “too long”. A sort of stuttering…
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VLC player (yes, the well-known one) setting playback speed at 0.30x: quite better than the previous one, but there’s still a (minor) stuttering/reverb effect. Apart from this, the sound (it’s a human speech, actually) is kept quite natural, as in the previous effect.
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Audacity’s “Sliding Time Scale/Pitch Shift” effect: much smoother than the two above, very nice, but also rather “metallic” (a new side effect, not present in the other two effects - I said they were quite “natural”, indeed).
Ok, I know that: talking about tempo-change algorithms, it’s difficult to get perfect results, and we can’t have our cake and eat it too, but I was wondering if there’s one more effect to test or a way to adjust settings for the two mentioned above. I remember, since I had a look to it several years ago, that Adobe Audition (does it exist anymore?) included a main filter to change audio speed (keeping the pitch) where one could set, for example, the length of the micro-portions of audio that would have been used to “create” data where there were not (or a sort of that). Is this possible in Audacity, some way?
By the way, I was surprised when I listened to the performance of VLC player slow-downing “filter”: it’s much better than Audacity’s “Change Tempo”. Unfortunately, the “Sliding Time Scale/Pitch Shift” makes the human voice so metallic that I’d like to find an even better result.
I hope you have a greater knowledge than me to help me find a solution to this “problem”…
Thank you so much in advance.
Falco
P.S.: please forgive me if I did any language mistake, I’m not an English native speaker 
