Hey Steve,
Sorry to hear about that. Three years ago I lost low frequency hearing in my right ear. For a while I was hearing a weird harmony on certain notes, as well as weird robotic sounds. After about 6 months or so, the robotic sounds and weird harmonies thankfully disappeared, but I'm still left with the low frequency hearing loss. Thank God for spectrum analyzers! Low frequency hearing loss is rare, and doesn't usually have anything to do with listening to loud music, or so I was told. The ENT I went to when it first happened gave me a series of of steroid injections into the ear, but sadly did not work. The ENT said it was probably caused by a weird virus.