hope im in the right spot. [WinXP - w/Audacity 2.0.4]
I have a Sansa Clip (mp3 player) with a feature on it for recording voice. It delivers 24 kHz mono wave (PCM) files (16 bit, 384k). I like to play with these audio files with Audacity.
Question: with these Sansa Clip files when editing should I keep their original 24khz audio sample rate for best quality? I am recording acoustic guitar and vocals and of course want to get the best quality through Audacity when editing. Sometimes I keep mono, sometimes I create stereo. And ocassionally combine tracks (then render together).
I am not that experienced w/all this – But I am still unclear on this… Like, if I add effects, duplicate, multi track, make stereo, etc. with Audacity --can that (combined) exceed the original recording’s ‘frequencies’? --thus the end result be improved by ‘upsampling’ --from it’s original 24 kHz to the standard 44.1 kHz?
A given sample rate cannot contain frequencies higher than half that rate.
If you resample the project to 44100 Hz (change the project rate bottom left then Tracks > Resample) you can add audio in another track that could contain frequencies up to the human upper limit of hearing (which is about 20000 Hz). If you mixed that track into the other original tracks then the original tracks could also contain that additional higher frequency audio.
You could increase speed using Effect > Change Speed (also increasing pitch) or increase pitch using Effect > Change Pitch (without affecting tempo) to increase all the existing frequencies pro rata up to half the sample rate. If you had resampled to a higher rate, Change Speed or Change Pitch could then make the highest frequencies in the recording exceed 12000 Hz.
But you cannot restore frequencies you originally failed to capture because the sample rate of the recorder was too low.
“Most” effects and editing will not make any difference to the upper frequency range, but there are some that can - for example (deliberate) distortion effects will generate high frequencies, modulation and pitch shifting effects may introduce higher frequencies. Normal editing (cut/copy/pasts) should not change the frequency range.
If you will be adding other sounds (either recording or importing) then as Gale advised, it will probably be best to set the project rate to 44.1 kHz.
If the final destination is an audio CD, then since audio CDs are always 44.1 kHz it will need to be resampled at some point, so I’d do it straight away. It will do no harm to convert to 44.1 kHz sample rate.
“Harmonic Enhancer” effects are intended to be able to “fake” better quality by generating overtones, but in my experience they are not usually very useful for “acoustic” style sounds. (they can work quite well for brightening up dull cymbal or snare drum recordings).