So I looked back at his medical records...

I first brought up problems with his hearing in Feb. 2012.

He was screened six months later. Here are the results:

Left:
500hz: 20db
1000hz: 5db
2000hz: 5db
4000hz: 5db

Right:
500hz: 20db
1000hz: 15db
2000hz: 5db
4000hz: 5db

This was considered a pass but I am learning (by lots of googling) that maybe this was a borderline pass and maybe indicative of some hearing loss.

He has several risk factors for hearing problems - preterm, NICU, jaundice

Anyone more familiar with these test?

His teacher also mentioned last year that he had trouble distinguishing between similar sounds. He makes similar errors when speaking.