I am not sure what the scientific basis is but early ear infections came up with pretty much every developmental type person we've seen about our kids - paeds, OTs, speechies, psychologists. They all see it as either causal or at least correlated with a bunch of conditions, all of which tend to include the above issues in their symptoms.
And my kids have not had a single ear infection between them. They do have ear wax like you wouldn't believe, my youngest has had to have it dug out by an ENT on a regular basis (we take her each time her diction devolves and she seems to be mishearing).
