Lisping in Young Adults

Much of my research on lisps, all types, has reported that lisping is common in young children, and with the proper speech therapy can be nonexistent. One of the studies that I read about was done of young adults. These young adults were entering students at Ghent University in Belgium, in the speech language pathology department. The study was done because many of the young adults that had previously entered the university still presented frontal lisping problems at an older age.
The actual experiment was that 748 students were video-recorded reciting the Dutch version of a text from the International Phonetic Association. Of the 748 students, it was equal parts of 374 males and females. The video recording yielded a 23.3% presence of lisping in the students. There was no difference found between males and females. The conclusion of the study showed that due to the high percentage of lisping found in young adults, maybe lisping continuing into an older age is quite normal in adults.