I recall a style of language learning where you listen to CDs in which your language and the foreign language are spoken simeltaneously. For example "Hello" is said in one earbud while "Bonjour" is said in the other earbud. What is this style of teaching called?
This method of learning languages seems to be called Bilingual-Dichotic Method. (Dichotic: involving or relating to the simultaneous stimulation of the right and left ear by different sounds.)
Here are two relevant links. The first is to a scientific study: Bilingual-Dichotic Learning of Foreign-Language Vocabulary: Visual Cued-Recall and Phrases.
This study actually claims that vocabulary acquisition using the Bilingual-Dichotic Method "yielded statistically significantly superior learning performances, averaging 10-18% more correct responses" than when using conventional diotic methods (where "either the foreign word is presented twice to both ears or the native word is followed by the foreign word").
The second link is to a short article on a site dedicated to memory and learning (which article sadly doesn't offer any further citation or links to scientific sources): Bilingual-Dichotic Method.
Edit: After doing a small search on the Internet I found two "mixed media products" using the bilingual-dichotic method, both from a certain Louis Aarons, the author of the study mentioned above... This doesn't necessarily mean that there is something wrong with the study, but there does seem to be a possible conflict of interest.