T.N.
Yes, I would definetely test his hearing and vision. My son also does not respond all the time to questions but he is attending preschool through the school district for a speech delay. He is 4. Please have the school evaluate him, even if he just got pull out services for speech or got extra academic support, it would help. He may just be shy and immature, that's why socially it may help to hold him back. Also, if they think that he has a speech impairment get him tested privately with a skilled speech pathologist perhaps affiliated with a university or through a referral. Also, I would also see an ENT to make sure there are no structural problems. His speech may be the catalyst for his apparent other "problems". Good luck.