It is a particular kind of think aloud protocol (or TAP) created by Stefano Federici and Simone Borsci[1] at the Interuniversity Center for Research on Cognitive Processing in Natural and Artificial Systems[2] of University of Rome "La Sapienza".
Nevertheless, when a usability evaluation is carried out with blind people several studies propose to use the retrospective TAP: indeed, using a screen reader and talking about the way of interacting with the computer implies a structural interference between action and verbalization.
Undoubtedly, cognitive studies provide a lot of evidence supporting the idea that individuals can listen, verbalize, manipulate, and rescue information in multiple task conditions.
As Colin Cherry[4] showed, subjects, when listening to two different messages from a single loudspeaker, can separate sounds from background noise, recognize the gender of the speaker, the direction, and the pitch (cocktail party effect).
Moreover, K. Anders Ericsson and Walter Kintsch[5] showed that, in a multiple task condition, subjects' ability of rescuing information is not compromised by an interruption of the action flow (as it happens in the concurrent thinking aloud technique), thanks to the “Long Term Working Memory mechanism” of information retrieval (Working Memory section Ericsson and Kintsch).