Listening Effort and Speech Recognition with Frequency Compression Amplification for Children and Adults with Hearing Loss

Abstract

Background Nonlinear frequency compression (NFC) can improve the audibility of high frequency sounds by lowering them to a frequency where audibility is better; however, this lowering results in spectral distortion. Consequently, performance is a combination of the effects of increased access to high frequency sounds and the detrimental effects of spectral distortion. Previous work has demonstrated positive benefits of NFC on speech recognition when NFC is set to improve audibility while minimizing distortion. However, the extent to which NFC impacts listening effort is not well understood, especially for children with hearing loss. Purpose To examine the impact of NFC on recognition and listening effort for speech in adults and children with hearing loss. Research Design Within-subject, quasi-experimental study. Participants listened to amplified nonsense words that were 1) frequency-lowered using NFC, 2) low-pass filtered at 5 kHz to simulate the restricted bandwidth (RBW) of conventional hearing aid processing, or 3) low-pass filtered at 10 kHz to simulate extended bandwidth (EBW) amplification. Participants were blinded to the type of processing. Participants’ responses to each nonsense word were analyzed for accuracy and verbal response time (listening effort). Study Sample Fourteen children (8–16 years) and 14 adults (19–65 years) with mild-to-severe sensorineural hearing loss. Intervention Participants listened to speech processed by a hearing aid simulator that amplified input signals to fit a prescriptive target fitting procedure. Results Both the children and adults identified the nonsense words and initial consonants better with EBW and NFC than with RBW. The type of processing did not affect the identification of the vowels or final consonants. There was no effect of age for recognition of the nonsense words, initial consonants, medial vowels or final consonants. Verbal response time did not change significantly with the type of processing or age. Conclusion Both the adults and children demonstrated improved speech recognition with access to the high-frequency sounds in speech. Listening effort as measured by verbal response time was not affected by access to high-frequency sounds.

Perceptual Benefits of Extended Bandwidth Hearing Aids With Children: A Within-Subject Design Using Clinically Available Hearing Aids

“…Fit-to-target deviations were within 2-dB root-mean-square error (RMSE) using 0.5, 1, 2, and 4 kHz, for speech input levels at 55, 65, and 75 dB SPL, within 4-dB RMSE when including 6 kHz and within 10 dB when including 8 kHz. These values are within the recommended 5-dB RMSE for frequencies up to 6 kHz for hearing aid fitting (Baker & Jenstad, 2017;Brennan et al, 2017;McCreery, Bentler, et al, 2013). For the maximum power output test signal, the values were within 3 dB for frequencies up to 4 kHz, within 5 dB for up to 6 kHz and within 12 dB up to 8 kHz.…”

The use of ecological momentary assessment to evaluate real-world aided outcomes with children

“…Fit to target deviations were within 2 dB root mean square error (RMSE) using 0.5, 1, 2 and 4 kHz, for speech input levels at 55, 65 and 75 dB SPL, within 4 dB RMSE when including 6 kHz, and within 10 dB when including 8 kHz. These values are within the recommended 5 dB RMSE for frequencies up to 6 kHz for hearing aid fitting (Baker and Jenstad 2017;Brennan et al 2017;McCreery, Bentler, and Roush 2013). For the MPO test signal, the values were within 3 dB for frequencies up to 4 kHz, within 5 dB for up to 6 kHz, and within 12 dB up to 8 kHz.…”

Understanding Variability in Individual Response to Hearing Aid Signal Processing in Wearable Hearing Aids

“…Frequency compression has generated more treatment uncertainty, with studies of adult listeners showing only a subset of treated individuals received benefit (Picou, Steven, & Ricketts, 2015;Souza, Arehart, Kates, Croghan, & Gehani, 2013). This finding has been proposed to be related to the level of signal manipulation versus the improvement in audibility (Brennan, Lewis, McCreery, Kopun, & Alexander, 2017;Souza et al, 2013). Presumably, if improved audibility is the dominant effect, speech recognition will be better with frequency compression.…”