Many people with a sloping high-frequency hearing loss do not find the amplification provided by conventional hearing aids satisfactory. In particular, if the loss is severe to profound across a range of higher frequencies, it is unlikely that amplification will provide adequate audibility of all speech sounds without causing discomfort. One way of improving audibility for such people is to lower selected high-frequency sounds. This can be achieved by using a frequency-transposing hearing aid. In a recent comparison of the AVR TranSonic hearing aid with conventional amplification, moderate improvements in speech perception were found for four of the five subjects who participated in the trial. However, most of the improvement was associated with the TranSonic's amplification characteristics in the low frequencies, with only two subjects obtaining benefit specifically from the frequency transposition. In another study, psychophysical investigations were conducted with five different subjects who had a very steeply sloping loss. The results showed local improvements in frequency discrimination, and changes in loudness perception, at frequencies just below the edge of the loss. It is postulated that neural plasticity may account for these findings. A further study investigated whether frequency lowering might be beneficial to these people. Unfortunately, the results of speech perception tests showed that no significant improvements were provided by a simple form of transposition, even after a period of auditory training.