I have some hydrophone recordings recorded at 192KHz/24 bit. I think this hydrophone can capture up to around 80KHz. I’d like to listen to what is there over 15-20KHz. What is the best way to do that within Audacity - ‘Change Pitch’ or ‘Change Speed’? Or is there a better way?
Thank you
“Change Pitch” retains the original time base. That is, 1 minute of recording time will play in 1 minute.
The downside is that the sound will be distorted quite a lot with a big shift in pitch.
“Change Speed” retains the exact waveforms, so the sound quality is near perfect but lower in pitch and slower (like playing a record or tape at the wrong speed).
An even quicker / easier way would be to simply change the track sample rate. (See: Rate)
Reducing the sample rate from 96 kHz (96000 Hz) to 48000 will halve the frequencies (pitch) and halve the speed (double the length).
Reducing the sample rate from 96000 to 22050 will reduce the pitch and tempo by a factor of about 4.35.
The main advantage of doing it this way is that you can exactly reverse the effect back to the original, simply by changing the track sample rate back to 96000.
Wow -that’s very clear and concise - thank you. I didn’t know the issue about pitch-shifting - good to know. I’ll try the sample rate approach
I am now having a play with this. How do you advise that I change the sample rate of the recording? I have changed the Project Rate in bottom left of the editing window but it is not pitch shifting the recording but maybe just sample rate converting the playback at normal speed? Thoughts?
To achieve the required “stretching”, you just need to change the “Track Rate”:
(Click the link “Rate”)
Thank you. I have since found that and it works a treat.