IT is not too long ago that the computer-generated voices on interactive telephone answering systems were so irksome that callers could not hang up fast enough. More recently, computer response systems have become friendlier, and are starting to prove their worth. Hong Kong interactive voice response specialists IVRS International plans to use next month's Voice Asia '94 conference and exhibition to launch its new generation RobotOperator. ''The applications [for interactive voice response systems] are really only restricted by the imagination because the technology is actually quite mature,'' said IVRS International managing director Kenneth Wong. The RobotOperator, developed by InterVoice of the United States, is a PS/2-based system designed to act as an interface between a caller and a computer database - in English, Cantonese, Mandarin, or Japanese. It is probably best known as the new voice-activated ticket-booking system at United Artists Cinemas. ''The system interacts with callers, prompting them to dial digits to obtain data or convey requests,'' Mr Wong said. Voice Asia '94 is scheduled for May 3 to 5 at the Hong Kong Exhibition and Convention Centre.