Children with Moderate Hearing Loss and Non-Linear Frequency Compression
Wolfe et al (2011) evaluated 15 children with moderate to moderately severe hearing loss (aged 5 to 13 years) with regard to their speech recognition ability after six months experience using non-linear frequency compression (NLFC).
The authors reviewed general types of frequency-altering technologies, such as frequency transposition (in which all frequencies are shifted downward, above a certain target, such as 2500 Hz), linear frequency transposition (in which dominant components of a one octave-wide band are essentially shifted to the next lower octave), and non-linear frequency compression (in which high frequency inputs are compressed by a clinician-selected ratio and are shifted to a lower frequency range to enhance audibility).
Wolfe et al concluded that NLFC significantly improves audibility for high-frequency sounds and recognition of speech sounds. Continued improvement (with regard to recognition of speech sounds while using NLFC) continues after six months. Improvements in speech recognition in noise (with NLFC) continue after several weeks and/or months of use. This study supports NLFC use for children with moderate, flat, sloping to profound high-frequency hearing loss.
For more Information, References and Recommendations
McDermott H, Henshall K. (2010) The Use of Frequency Compression by Cochlear Implant Recipients with Postoperative Acoustic Hearing. Journal of the American Academy of Audiology 21(6):380-389.
Wolfe J, John A, Schafer E, Nyffeler M, Boretzki M, Caraway T, Hudson M. (2011) Long-Term Effects of Non-Linear Frequency Compression for Children with Moderate Hearing Loss. International Journal of Audiology 50:396-404.