EXTENDED/ENHANCED/VOODOO...What's the Difference?

I consider these 3 types of audio in amateur radio to be very different in nature and approach.
"Extended" I associate with audio that is transmitted  in a wider bandwidth than normal.
Lets say wider than 2.8-3 khz. This allows a silkier top end that is not achievable running below 3.6 khz.
There will always be a certain harshness in the transmitted audio below 3.6 khz. Understanding
where the human voice sits in the audio spectrum is key in setting up your gear be it eq/exciters.
Generally, the articulation of the human voice occupies a bandwidth of app' 800hz to 2khz. That
is pretty narrow but is a key frequency bandwidth to allow people to understand what you are saying.
Now, with that in mind, what happens when we push our transmitted audio beyond 3 khz? Now you can
bring in more of the nice silky articulate top end without the harshness that occurs around 2-3 khz.

What about the bottom end you're asking? 

The "badda boom"....How do we get that nice, big larger than life bottom end? Well, here's where it gets interesting. I have found that some conventional transceivers (non sdr's) are still capable of tremendous bottom end well below 100hz. One example is the ic7300. The maximum advertised BW of the 7300 is 100-2.9 khz. However, I am able to push audio from 40hz to 3.1 khz via brute force. This is where a simple eq isn't gonna do it. Enter the Aphex Aural Exciter with optical big bottom or as in what I am using currently, a DAW with the Antress "Modern Exciter" plugin. It allows me to push the bottom end well below 100hz to 40hz and the top end to 3.1 khz although the rig is not designed to do it. This would fall into the classification of "Enhanced" because it's not truly "extended single sideband." The bandwidth is still pretty limited although the bottom end has been extended considerably. The issue is that these transceivers are "brick walled" at the top and there's pretty much nothing that can be done about it.

What about Voodoo Audio?

Now that we have looked at the difference between extended and enhanced ssb, we can take a look at
"Voodoo" audio. Voodoo audio is what I would consider "larger than life" audio with a tremendous bottom end. Something that can only be appreciated when using a fairly decent monitoring system or excellent pair of headphones. A system capable of reproducing audio from 20-10khz. I use a pair of Edifier reference speakers and a Polk Audio subwoofer on my station. That way I can appreciate it. I consider voodoo audio to be purely subjective. Some folks love it. Some hate it. I like it but approach it from a slightly different aspect. In my view, having a big bottom end without an equally transparent top end is useless to me. If I'm going to push the bottom end to thunderous levels, I am going to have a top end that can shatter glass but not be too harsh. It's a tightrope that is very difficult to traverse. I hear very few stations on the air that can find that balance, and is a never-ending pursuit. The main problem is that most transceivers transmit the audio you are putting into them different than what you hear before the rigs.

What if I don't have the "Barry White" type of voice?

All is not lost. There are plenty of stations I hear running wide with absolutely beautiful audio. It is a worthy pursuit and will only improve the communications quality of the qso's. The issue here is that you can't tweak it if it isn't there to begin with. It all starts with your "pipes" and then the microphone. Don't let anyone ever tell you that the mic won't make a difference. They are a liar or they have no idea what they are talking about. Try it. You'll quickly realize it will make or break your sound. Especially on the sdr rigs where you can run wide.