KIEFER SUTHERLAND - SUTHERLAND TRYING TO DISCOVER CAUSE OF DEAFNESS

Hollywood actor KIEFER SUTHERLAND is baffled by his partial deafness - because he's yet to find the cause of it.

Sutherland, 37, can't hear anything in his left ear, which can prove to be problem when he's playing JACK BAUER on the set of his hit TV show 24.

He says, "I'm half deaf in one ear. I don't know what it's attributed to. It's happened over the last four or five years. It gets frustrating sometimes.

"It's not so severe that I can't function daily, but it gets frustrating when I have a phone to (my good) ear, and I've got an actor off-camera, talking to me.

"I have a very hard time hearing (them). It's more frustrating for them, actually, because they have to yell."

Sutherland is still trying to discover the cause of his problems.