It's mainly speech quality (sometimes called 'chest' voice). It feels very similar to speaking, hence the name, and the physical set up is the same, maybe retracted false vocal folds though (see below).

There are times that he moves higher in the range where's its more difficult to sustain, however with some appropriate muscle support he's able to sustain this.

There are some occassional higher (much higher) which he uses a new voice quality – twang (sometimes called mix)! Think nyah nyah nyah nyah nyah – brassy, annoying and bright. They balance quite well with the speech quality as they are both loud. One or two of these may have been falsetto (breathy).

The end is just a vocal slide with constriction. For vocal slides, try singing weeeeeeeeee as if you're going down a slide, then back up. It's quite easy. Constriction may be dangerous – so be responsible! It will probably come naturally if you force the slide slightly at the top end of the range. Here's a video on how to conciously control them:

Http://www.youtube.com/watch?v=j5plYpgDx…

Its not really a vocal technique its more like a singing style…You let out a little air to give your vocals that kinda "yelp" sound….Alot of male singers in do it..A vocal technique would be like Mariah Careys "whistle note"…..

Buy Seth Riggs speech level singing book and it will help you with vocal endurance.