With the babies unable to differentiate from And when the babies used a different teether that did not block tongue movement, they once again appeared to comprehend the difference between the Ds. The study is in the Proceedings of the National Academy of Sciences. So is it time to pull the pacifier? "At this point I don't think that these data suggest parents should be taking away teething toys or soothers. The majority of infants are chewing on something semi-regularly throughout the day, and probably not doing it all day and every day. And most of these infants do go on to develop speech normally." So not to worry. Bruderer says the research might instead offer insight into how children with oral motor impairments or cleft palate perceive speech now that we know the tongue really does matter, when first learning it.