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Best way to mask a voice? Pitch & Harmony Plugins
Old 20th December 2010
  #1
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petsematary's Avatar
 

Best way to mask a voice?

I'm editing a hush-hush wiretap recording and I need to mask one of the voices to make sure he/she/it can't be recognized. Never done this before, any suggestions on how to do? Using simple Audacity setup here, maybe there's something built in or a vst I could download, lemme know if you have any experience in this.
Old 20th December 2010
  #2
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Ask Teddy Riley, he managed to do just that on MJ's new album.
Old 20th December 2010
  #3
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Most of the time when I hear this sort of thing, the voice is masked by simple pitch-shifting. The trouble with this for me is that it seems that it would be simple enough to re-shift the voice back into its normal range where the voice could possibly be recognized...

If I had to bet my life (or someone else's life) that the voice was unrecognizable, I'd transcribe the original voice and have an actor re-voice the script for whatever broadcast use you have in mind. Even if the actor had to match video images of the original person reading (probably disguised or in half-light), you could easily do that...

Then, the original voice would be protected from recognition... or from decoding by someone with the tools and desire to hear the original voice.
Old 20th December 2010
  #4
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Quote:
Originally Posted by studiostuff View Post
Most of the time when I hear this sort of thing, the voice is masked by simple pitch-shifting. The trouble with this for me is that it seems that it would be simple enough to re-shift the voice back into its normal range where the voice could possibly be recognized...
good point. I always wondered why people assumed that criminals had no access to plug-ins.

Quote:
If I had to bet my life (or someone else's life) that the voice was unrecognizable, I'd transcribe the original voice and have an actor re-voice the script for whatever broadcast use you have in mind. Even if the actor had to match video images of the original person reading (probably disguised or in half-light), you could easily do that...

Then, the original voice would be protected from recognition... or from decoding by someone with the tools and desire to hear the original voice.

of course that actor had better keep a lookout over his shoulder!
Old 20th December 2010
  #5
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Ethan Winer's Avatar
 

Lightbulb

Quote:
Originally Posted by studiostuff View Post
it would be simple enough to re-shift the voice back into its normal range where the voice could possibly be recognized.
Good point, though there's a type of pitch shifting that most people don't know about called heterodyning. This is a non-musical method that shifts all frequencies by a constant number of Hz, rather than preserving their harmonic relations. So if someone shifted the effected voice back using "normal" pitch shift tools, it still won't sound like the original voice. You can download the freeware VST Bode Frequency Shifter here:

Christian’s Blog » Modulation

--Ethan
Old 20th December 2010
  #6
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Thanks! Yeah, that's what I was worried about, people changing it back and figuring out who the person is. This person (and I) might get in trouble if that happens. I will check out the plug, sounds right up my alley though.
Old 20th December 2010
  #7
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Will's Avatar
 

You could try pitch shifting and then running through a fast phaser. It will warble a bit, but would be very difficult to undo.
Old 21st December 2010
  #8
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Could you not use a tool like Melodyne to shift the pitch in such uneven values, that it would become increasingly difficult to turn back around?
Old 21st December 2010
  #9
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"Could you not use a tool like Melodyne to shift the pitch in such uneven values, that it would become increasingly difficult to turn back around?"

...Then using the formant control, alter it even more maybe? Then if someone is able to pitch shift it back, the formants will be skewed still
Old 21st December 2010
  #10
Logic has a Vocal Transformer with stuff like Robot Voice and stuff, one of the options is voice disguiser. Something like that would be best IMO.
Old 22nd December 2010
  #11
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The plug mentioned first was windows-only so I'll have to switch setups but it seems fine otherwise.
Old 22nd December 2010
  #12
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melodyne
Old 22nd December 2010
  #13
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Quote:
Originally Posted by Ethan Winer View Post
Good point, though there's a type of pitch shifting that most people don't know about called heterodyning. This is a non-musical method that shifts all frequencies by a constant number of Hz, rather than preserving their harmonic relations. So if someone shifted the effected voice back using "normal" pitch shift tools, it still won't sound like the original voice. You can download the freeware VST Bode Frequency Shifter here:

Christian’s Blog » Modulation

--Ethan
what about if they shift it back using the software you mention? Can they get back to "square one" that way?
Old 22nd December 2010
  #14
Quote:
Originally Posted by trippy View Post
what about if they shift it back using the software you mention? Can they get back to "square one" that way?
Not if they don't know which frequencies were shifted how. Effectively you change it using a key; if you don't have a key, you can't unlock the coded voice.
Old 22nd December 2010
  #15
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Ethan Winer's Avatar
 

Lightbulb

Quote:
Originally Posted by trippy View Post
what about if they shift it back using the software you mention? Can they get back to "square one" that way?
Yes, but it's unlikely someone would think to use such a non-standard type of pitch shifter.

--Ethan
Old 22nd December 2010
  #16
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Quote:
Originally Posted by Ethan Winer View Post
Yes, but it's unlikely someone would think to use such a non-standard type of pitch shifter.

--Ethan
Unless they were reading this thread.

Or came across it by Googling - "undo voice masking"
Old 22nd December 2010
  #17
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As far as I understand, this type of pitch shifting can't be undone and even I can't remember what values were set so it's a pretty safe bet no one's gonna notice. It worked nicely btw, I did it on a borrowed windows machine. Sounds pretty good - you can hear what he/she/it is saying but the voice is completely disguised. Sometimes I actually can't hear because the masking is too hard but this worked nicely. Thanks.
Old 23rd December 2010
  #18
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How did you swing the interview with Julian Assange?
Old 23rd December 2010
  #19
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AcoosticZoo's Avatar
What about a pitch shifter plugin but modulate the pitch manually using automation?

I uploaded an example using waves soundshifter with pitch automated. I also blended a vocoder into the signal for added security.

Much harder to "decode" due to a random human modulation --->


Regards
Josef Horhay
Mixing Engineer
www.acoosticzoo.com
Attached Files

Mask Voice.mp3 (650.9 KB, 144 views)

Old 24th December 2010
  #20
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Quote:
Originally Posted by Boschen View Post
How did you swing the interview with Julian Assange?
Know a guy who knows a guy, I would think. Or it could be Mad Max.
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