[LAU] Sub-Harmonic Synthesizer?

[Paul Coccoli]

On Sat, Mar 19, 2011 at 6:23 PM, Josh Lawrence <hardbop200 at gmail.com> wrote:
> Hi all,
>
> This past week I attending a concert of an acappella vocal group that
> would using a DBX-120A sub-harmonic synthesizer to double the bass
> singer's voice.  It sounded amazing, and a little Googling has
> revealed that this rackmount unit is quite popular.  Is there anything
> in the Linux world that does the same thing?  I am not a programmer,
> so it would need to be somewhat easy-to-use (trying to fend off the
> "just make one in puredata!!!" comments here :), lv2 would be awesome
> too.

Is this different than a pitch shifter?  Or does it actually
synthesize some waveform based on the frequency of the incoming
signal?