Paired Comparisons: Non-Linear Frequency Compression, Extended Bandwidth, and Restricted Bandwidth
Brennan et al (2014) evaluated whether stimulus type (music passages and spoken sentences in quiet), age of listeners (children and adults), and degree of hearing loss influenced the listeners’ preferences for non-linear frequency compression (NFC), extended bandwidth (EBW), or restricted bandwidth (RBW). For the RBW and the NFC conditions, 5000 Hz was used as the low pass setting and for EBW, the simulator was set to 11,000 Hz.
Sixteen children (aged 8 to 16 years) and 16 adults (aged 19-65) with mild-to severe hearing loss participated in the round robin protocol. The authors note that “although NFC has the potential to increase high-frequency audibility, the resulting spectral distortion in lower-frequency regions…could have detrimental effects on speech recognition….”
Participants preferred EBW and NFC (as compared to RBW) while listening to speech, despite no other overall preferences. Brennan et al state that their findings are consistent with the hypothesis that people generally prefer the widest bandwidth. Of note, while listening to music, people with less high-frequency hearing loss were more likely to prefer EBW. As high-frequency hearing loss increased, participants were more likely to prefer NFC.
For More Information, References, and Recommendations
Alexander JM. (2013) Individual Variability in Recognition of Frequency Lowered Speech. Seminars in Hearing 34(2):86-107.
Brennan MA, McCreery R, Kopun J, Hoover B, Alexander J, Lewis D, Stelmachowicz PG. (2014) Paired Comparisons of Non-Linear Frequency Compression, Extended Bandwidth, and Restricted Bandwidth Hearing Aid Processing for Children and Adults with Hearing Loss. Journal of the American Academy of Audiology 25:993–998.