The Meisner technique is a method of acting often held in contrast to Method acting. Fundamentally it is about channeling the power of your imagination to become the character. This isn't really different than what voice actors do on a daily basis, however there was one small perspective modification on applying the theory that fundamentally changed how I deliver voice.
Generally, as a voice actor you are trained to identify traits of a character (i.e. character pendulum, character bible, character reference, etc...) and then utilize these character traits in delivery. For example:
A noble knight read for a video game may have the character traits kind, large, and aged. A VO embodying these traits could result in a character sounding soft and smooth, utilizing a deeper tone, with a slight tinge of reminiscence on the voice.
A guy next door read for a commercial may have traits such as warm, not intimidating, and young. If a VO was embodying these traits the read could be light-hearted, with a higher natural voice tone, and a fast pace.
When utilizing the standard elements of character generation taught to voice actors, it is quite quick and easy to generate clear character stereotypes (albeit with slight nuances based on the natural tone of the voice actor). In my eyes this is similar to dressing up in a costume for the role, and taking it off when done. It is a convincing surface level delivery of voice over!
Applying Meisner theory in voice is slightly different, although you may use the same character queues referenced above, the voice actor changes where they start in their process. Whereas traditional character creation in voice starts with the question "Who and what are they?", Meisner starts with "Who am I?" and then asks the former question. Its a small difference, but has significant implications for delivery of sincere reads.
So what does this do exactly? Well, it makes every character developed unique to the actor as it is based within the experience of the actor. Whereas the traditional character development process is very good at creating stereotypes (as character decisions are made based on factual elements of the imaginary character), the Meisner approach leverages the genuine history of each individual actor, and grows the role out of this.
This process is beneficial for both commercial and character delivery alike. The end result is a role that has a history beneath the archetype, which brings about a much more believable delivery of the read. It adds that human element that is difficult to quantify or qualify that simply makes the delivery sound more sincere.