Scrambling voice for transcribing

[laddie.music2]

Hi there,

I need to scramble a bunch of voice recordings from phone calls for transcribing overseas.

The main request from the client is that they want it to be scrambled kind of how you hear it on 60 minutes when a interviewee doesn't want to be recognised, so they pitch it down etc and do other process's so it's not a simple case of pitching it back up to recognise who the voice is.

Does anyone know how this is done, and what is considered the kind of official way of doing this?

My first guess was to just use my waves plugins and do some pitch / formant adjustments to mangle it so it's transcribable but not 'recoverable' haha

Anyways, any help is very apprceiated.