Hi there, I am very new to all things audio-related, so you’ll have to bear with me and my ignorance. I am working in a social psychology lab and we are conducting a study on voice perception. I need to apply some kind of effect to the audio samples such that the content of the speech is unintelligible, but the pitch of the voice doesn’t change (very essential). Participants who hear the audio stimuli will be making certain judgments of personality and we are specifically correlating it with the pitch of the voices so that needs to remain constant, but we don’t want the actual content of the speech affecting their perception. I suppose I’m looking for an audio analog of blurring an image. I am playing around with Audacity now to see if I can stumble my way into the solution, but I thought I’d put it out there to all you experts. Thanks for any help!
Try this “reverso” effect.
It takes short sections of the sound and reverses them.
https://forum.audacityteam.org/t/reverso/21401/1
Instructions for installing the effect: http://wiki.audacityteam.org/wiki/Download_Nyquist_Plugins#Installing_Plug-ins
If reversing chunks, (i.e. playing backwards), modifies the speech too much , try chopping between the original and a time-shifted duplicate …
done using Robert J.H’s chopper code … automated silence interval - #9 by Robert_J_H
[ I christened this process Unwinisation 
]
The “PaulStretch” effect in Audacity will temporally (horizontally) blur the sound spectrogram :
the result is like very severe reverberation …
“Sine speech” may applicable , but people can learn to understand it …
http://www.lifesci.sussex.ac.uk/home/Chris_Darwin/SWS/
http://www.scholarpedia.org/article/Sine-wave_speech
Thank you both for the advice!! I’m going to try all these things 