one thing you could do that would help him is teach him the name of the strings and make it a fun game. also you could play the strings open and have him name the string as you do so without looking at which string you are playing and that would help with ear pitch training. theres lots of fun things you can do together,but i think if you can get his little ears trained a little and realy praise him for any accomplishments he makes. its just like teaching them what colors are what. just have him work on hearing a open string and then trying to tell you what it is by sound only. i have a 8 year old daughter and we do this and it is fun for her.it will take alot of patience on your part but i aasure you it can be done. i wish you and your boy alot of fun and luck. god bless