I want to know the answer to the following question:
What specific type of diphthongs were the less educated Dutch speakers in the countryside using in the 16th century?
All the background I'm provided with is that "Instead, he argues, this development has been artificially frozen in an "intermediate" state by the standardisation of Dutch pronunciation in the 16th century, where lowered diphthongs found in rural dialects were perceived as ugly by the educated classes and accordingly declared substandard.". Is that enough to answer the question?