The theory is that across cultures and linguistic groups there are five sounds, each with a meaning, that are used by infants before the language acquisition period.
As the infant matures past 3 months in vocalization, the sound reflexes become replaced with more elaborate babbling.
The two-disc set covered the five universal words of the language, methods of learning how to recognize the vocalizations and sounds, numerous examples of baby cries from around the world to "tune your ear," and live demonstrations of newborn mother groups experimenting with the language.
Linguistics experts point out that Dunstan's hypothesis has not been subjected to rigorous testing or academic scrutiny.
[5] The Dunstan company had, at one time, developed a clinical trial plan with Brown University researchers to test its claims, but abandoned it for consumer surveys and small-group observations in order "to hasten the development of a system that could be used by parents," skipping rigorous testing to go straight to market.