Have you gotten an audiology exam to fully exclude an actual hearing loss? Not just the superficial hearing screening at the pediatrician's.
You can ask the school to get him an FM system. This is a microphone that the teacher wears- he can have a little speaker at his desk that amplifies the teacher's voice.
Or donate $1500 or so and have a Surround Sound put in. Again, the teacher wears a microphone, and it amplifies her/his voice in an overhead loudspeaker. My hearing impaired son has that, but it can help kids with CAPD.
