Your argument is well-resourced, and your answer is well phrased. The article from Rush University Health Center is helpful, in that it gives pointers on how to prevent ear infections, but most of the evidence regarding a correlation between infections and earbuds is anecdotal, and doesn't suggest a pattern for a large population. That being said, your other resources, especially the International Journal of Medicine and Pharmacy, give real, solid evidence for a link between the two factors.