Also termed frequency compression or frequency lowering, it is used to describe how sound is manipulated in the output of high frequencies in hearing aids. For persons with a precipitously sloping high-frequency hearing loss, the amount of amplification that can be provided to aid those high frequencies has posed a problem for hearing aid users with this configuration of hearing loss. The technique of frequency transposition was developed to allow these high frequency sounds to be heard by “compressing”, “transposing”, or “lowering” them to a lower frequency where they can be detected.
Many hearing aid manufacturers have hearing aid models that are capable of providing frequency transposition. They are all called something different for branding purposes. For example, Starkey's frequency transposition system is called Spectral IQ and Phonak's is called Sound Recover. In addition to the name being different across manufacturers, the method at which frequency transposition occurs is different from manufacturer to manufacturer.
There has been a lot of recent debate concerning the benefit of frequency transposition hearing aids and whether it should be used and when it should be used. Some argue that it distorts the speech signal too much for it to be beneficial. Whether or not frequency transposition is used in a hearing aid will most likely depend on the preference of the Audiologist.