Wirelessly posted (Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_3_5 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8L1 Safari/6533.18.5)
I think you're just imagining things. I know the iPhone 4 has a significantly lesser sound quality than the iPad, and the MacBooks provide the best quality of all. Perhaps it's the hissing sound that comes from an ungrounded connection (in your Mac)?