I had a difficult time reading his chapter on musical hallucinations because every time Sacks would mention a piece of music I knew, I would hear it in my head. I can't say that I "suffer" from musical hallucinations, because I really enjoy having them. People often comment that I seem happy when they see me. It is probably because when I am out and about I always have something wonderful going through my head. I often dream about pieces of music, or I work out problems with something I'm writing by playing passages over and over in my head until they are fixed. I guess I am pretty lucky because I can control my musical thoughts and auditory hallucinations pretty much at will. There are people who cannot.
This book is a great companion to This is your Brain on Music (Sacks quotes Levitin often), because it explains to the non scientist in clearly-explained physical and neurological terms what actually happens in differently-wired people's brains when confronted with musical situations. Sacks writes as a neurologist, but he also writes and as a passionate music lover as well as a skilled amateur musician.