The common observation that hearing impairment tends to affect sound perception at high frequencies more than at lower ones has led recently to the development and evaluation of a number of innovative signal-processing techniques. These include frequency-lowering schemes that aim to provide improved audibility and discriminability of sound components by shifting them into a frequency range where the listener has less impairment. For people who have usable low-frequency hearing, but insufficient high-frequency hearing for effective use of a frequency-lowering hearing instrument, cochlear implantation is rapidly becoming a well-accepted option. The use of a cochlear implant, in combination with an acoustic hearing aid either in the implanted ear or the opposite ear, can provide large perceptual benefits, especially for understanding speech in noise and for listening to music. Selecting and fitting the most appropriate configuration of hearing devices is critical in maximising the perceptual benefits for both children and adults with severe high-frequency hearing impairment.