high quality digital audio recorder-mac compatible

Hi there,

I'm trying to find a mac-compatible high quality digital audio recorder for my husband who is interested in experimenting with sound art. Not music so much as recording things like the sound of ice freezing and manipulating voices etc. He needs something really sensitive and sharp, but durable. I understand there's a type that you can wear ear buds and the buds record the sounds as you hear them. Does anyone know what this is called? Where I can look for it? What some brand/model names are? Any other suggestions?

Thanks so much in advance,
Diane