Who are candidates for nonlinear frequency compression?
Nonlinear frequency compression (NFC) such as Phonak's proprietary SoundRecover algorithm compensates for hearing loss in frequency ranges where traditional amplification on its own does not provide sufficient benefit. SoundRecover is designed to compress and thereby shift high frequencies into an adjacent area of audible hearing, without compressing or altering frequencies below the SoundRecover kneepoint. This unique approach results in the absence of artifact, and enables improved speech understanding as well as audibility of high-frequency cues such as birds singing, alarm clocks, and the like. In addition, SoundRecover is designed to eliminate the interfering feedback and discomfort that often results from high levels of high frequency amplification.
The effectiveness and benefits of NFC have been shown for all degrees of hearing loss. Most recently, Glista et al. (2009) evaluated NFC with children and adults with sloping, high frequency hearing loss. The study's group level results provided evidence of significant improvement of consonant and plural recognition when NFC was enabled. Overall, the study's results suggested that NFC processing can improve high frequency speech detection and speech recognition ability for both adults and children.
Boretzki and Kegel (2009) examined the benefits of SoundRecover for subjects with mild hearing loss, using an adapted phoneme test, a research tool developed to measure thresholds at which high-frequency speech components could be correctly identified. Their findings suggested that SoundRecover has the potential to provide substantial improvement in the acquisition and identification of high-frequency speech signals and environmental sounds when compared to conventional high-end digital amplification. Further, test subjects in this study subjectively perceived hearing with SoundRecover as more comfortable than without.
Wolfe and colleagues (2009) reported that although children with mild to moderately severe hearing loss typically receive considerable benefit from hearing aids, they frequently have difficulty with certain aspects of speech recognition and production. However, providing sufficient amplification for high-frequency phonemes is critical for the development of language and speech production. They evaluated NFC in 16 children with a mild to moderate hearing loss using the Plural Test developed by Susan Scollie and colleagues (Glista et al., 2009) from the University of Western Ontario (UWO Plural Test). Results showed improve acquisition and identification of high-frequency speech signals and environmental sounds compared to conventional high-end digital amplification. Wolfe concluded that this type of full-time access to inputs across the entire speech range is critical for developing age-appropriate speech, language, and auditory skills. He further states that it is possible that using NFC can enable young children to overcome many of the deficits that have been found in children with mild to moderate hearing loss. He suggests that NFC should be considered as an option for children with mild to moderately severe hearing loss.
Likewise, the benefits of SoundRecover for individuals with moderately-severe to profound hearing loss is also well documented (e.g., Simpson, Hersbach & McDermott, 2005, 2006;Nyffeler, 2008a). In addition, Nyffeler (2008b) reports on a study conducted at the University Clinic of Mainz in Germany that evaluated eleven adult participants with moderately-severe sensorineural hearing loss. This study concluded that SoundRecover significantly improved the listening experience in quiet and noisy situations, as well as increased the pleasantness of environmental sounds and subject's own voice, resulting in a highly satisfactory overall impression.
Thank you for your question. For more information about SoundRecover, please visit:
www.naida.phonak.com. In addition, Phonak offers several live and recorded courses on SoundRecover on AudiologyOnline - for more information or to register, visit the Phonak Web Channel on AudiologyOnline.
Boretzki, M., Kegel, A. (2009, April). The benefits of SoundRecover for people with mild hearing loss. Phonak AG: Phonak Field Study News.
Glista, D. , Scollie, S., Bagatto, M., Seewald, R., Parsa, V., Johnson, A. (2009). Evaluation of nonlinear frequency compression: Clinical outcomes. International Journal of Audiology, 48(9), 632-644.
Nyffeler, M. (2008a). The Naída Power hearing instrument family - Field Test Results demonstrate better speech clarity - unparalleled in its class. AudiologyOnline, October 2008.
Nyffeler, M. (2008b). Study finds that nonlinear frequency compression boosts speech intelligibility. The Hearing Journal, 61(12), 22,24,26.
Simpson, A., A.A. Hersbach and H.J. McDermott, (2005). Improvements in speech perception with an experimental nonlinear frequency compression hearing device. International Journal of Audiology, 44(5), 281-92.
Simpson, A., A.A. Hersbach and H.J. McDermott, (2006). Frequency-compression outcomes in listeners with steeply sloping audiograms. International Journal of Audiology, 45(11), 619-629.
Wolfe, J., Caraway, T., Andrew, J., Schafer, E. C. Nyffeler, M. (2009). Study suggests that non-linear frequency compression helps children with moderate loss. The Hearing Journal, 62(9), 32-35.
Dr. Myriel Nyffeler is a biologist and earned her doctorate degree in the field of Neurobiology at the Swiss Federal Institute of Technology (ETH) in Zurich. She is the Scientific Marketing Manager at Phonak AG in Stäfa, Switzerland in charge of Phonak's international Field Studies.