These results suggest that LFT is a potentially useful hearing aid feature for school-age children with a precipitous HF sensorineural hearing loss.

Patients with a precipitous high-frequency hearing loss pose a unique challenge for dispensing audiologists. Hearing aids rarely provide sufficient high-frequency gain without over-amplifying the lower frequencies, which results in poor sound quality or significant sound distortions. The occlusion effect and upward spread of masking may also occur. For these patients, the high frequencies are not easily reachable. Recently it has been suggested that a precipitous loss may make the high frequencies non-functional, "dead," or unaidable. Some studies suggest a decrease in word recognition scores when these "dead" regions are amplified. This result casts doubt on the usefulness of amplifying such a region. For people with either an unaidable or unreachable high-frequency hearing loss, information carried in those frequency regions would not be available despite the use of amplification. What Is Frequency Lowering? Audibility of unaidable or unreachable high-frequency information is achieved by converting that information to the lower frequencies where hearing is aidable or reachable. This conversion process is called frequency lowering. For example, information carried at 4000 Hz may be "lowered" to 2000 Hz so that it is heard as 2000 Hz. It is important to recognize that frequency lowering doesn't restore hearing in the original high frequencies. Instead, the signals are heard at a lower frequency. For this reason, a frequency-lowered signal will initially sound "unnatural" to most listeners. Historical Results The concept of frequency lowering is not new. Braida, Durlach, Lippmann, Hicks, Rabiowitz, and Reed (1979), in an excellent review of frequency-lowering techniques, dated studies on the topic beginning in the 1950s. Early attempts at frequency lowering implemented on analog technologies made it difficult to achieve the desired signal-processing results without introducing significant artifacts, such as unnatural-sounding speech and distorted temporal and rhythmic

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