Nonlinear frequency compression: Influence of start frequency and input bandwidth on consonant and vowel recognition

Alexander, Joshua M.

doi:10.1121/1.4941916

Cited by 23 publications

(30 citation statements)

References 46 publications

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“…Performance was higher for the nasals, affricates and stops than for the fricatives, which is similar to the pattern identified by Alexander (2016) for consonants in the medial position. Two repeated-measures ANOVAs, one each for initial and final consonants, were completed using within-subject factors of consonant and processing.…”

Section: Resultssupporting

confidence: 83%

“…The filter bank consisted of eight one-third octave-band filters with center frequencies spaced between .25 and 6.3 kHz. The NFC circuit used an algorithm described by Simpson et al (2005) and others (Alexander, 2016; Brennan et al, 2014; McCreery et al, 2013, 2014). …”

Section: Methodsmentioning

confidence: 99%

“…The maximum audible input frequency with NFC was 8240 Hz for all participants (maximum audible output frequency = 5 kHz, start frequency = 3.8 kHz, compression ratio = 2.6), except two participants who had a maximum audible input frequency of 6960 Hz with NFC (maximum audible output frequency = 4 kHz, start frequency = 2.7 kHz, compression ratio 2.3). More details about the NFC processing in the hearing aid simulator and the fitting method are described by Alexander (2016), Brennan et al (2014) and McCreery et al (2013, 2014). …”

Section: Methodsmentioning

confidence: 99%

“…In general, benefit from NFC is better when access to high frequency sounds is increased with NFC (McCreery et al, 2013, 2014) but spectral distortion is minimized (Souza et al, 2013) as well as in listeners with greater high-frequency hearing loss (Brennan et al, 2014; Glista et al, 2009; Souza et al, 2013; but see Kokx-Ryan et al, 2015). Benefit is more likely to occur for stimuli where high-frequency audibility contributes to recognition (Hopkins et al, 2014; Kokx-Ryan et al, 2015; Wolfe et al, 2010, 2011), with decreases in recognition sometimes occurring for specific consonants or vowels (Alexander 2016; Kokx-Ryan et al, 2015). Lastly, individual variability in the ability to utilize the frequency-compressed information (Arehart et al, 2013; Ellis & Munro 2015; Glista et al, 2009; Souza et al, 2013) and acclimatization (Dickinson et al, 2014; Glista et al, 2012; Hopkins et al, 2014; Wolfe et al, 2011) may have also contributed to disparate findings across studies.…”

Section: Speech Recognitionmentioning

confidence: 99%

“…Stelmachowicz et al, 2001); consequently, we hypothesized that children would benefit more from the provision of high-frequency speech sounds (EBW and NFC) than adults. Because other studies have documented changes in the recognition of specific consonants (Kokx-Ryan et al, 2015) and vowels (Alexander, 2016) with NFC, we also examined the recognition of the individual consonants and vowels across the three bandwidth conditions. Lastly, we examined the potential contribution of degree of high-frequency hearing loss, age at which hearing-loss was identified, age of amplification, and hearing-aid use to benefit with NFC and EBW.…”

Section: Listening Effortmentioning

confidence: 99%

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

et al. 2017

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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.

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Section: Resultssupporting

confidence: 83%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Speech Recognitionmentioning

confidence: 99%

Section: Listening Effortmentioning

confidence: 99%

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

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The impact of hearing aids and age-related hearing loss on auditory plasticity across three months – An electrical neuroimaging study

et al. 2017

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The present study investigates behavioral and electrophysiological auditory and cognitive-related plasticity in three groups of healthy older adults (60-77 years). Group 1 was moderately hearing-impaired, experienced hearing aid users, and fitted with new hearing aids using non-linear frequency compression (NLFC on); Group 2, also moderately hearing-impaired, used the same type of hearing aids but NLFC was switched off during the entire period of study duration (NLFC off); Group 3 represented individuals with age-appropriate hearing (NHO) as controls, who were not different in IQ, gender, or age from Group 1 and 2. At five measurement time points (M1-M5) across three months, a series of active oddball tasks were administered while EEG was recorded. The stimuli comprised syllables consisting of naturally high-pitched fricatives (/sh/, /s/, and /f/), which are hard to distinguish for individuals with presbycusis. By applying a data-driven microstate approach to obtain global field power (GFP) as a measure of processing effort, the modulations of perceptual (P50, N1, P2) and cognitive-related (N2b, P3b) auditory evoked potentials were calculated and subsequently related to behavioral changes (accuracy and reaction time) across time. All groups improved their performance across time, but NHO showed consistently higher accuracy and faster reaction times than the hearing-impaired groups, especially under difficult conditions. Electrophysiological results complemented this finding by demonstrating longer latencies in the P50 and the N1 peak in hearing aid users. Furthermore, the GFP of cognitive-related evoked potentials decreased from M1 to M2 in the NHO group, while a comparable decrease in the hearing-impaired group was only evident at M5. After twelve weeks of hearing aid use of eight hours each day, we found a significantly lower GFP in the P3b of the group with NLFC on as compared to the group with NLFC off. These findings suggest higher processing effort, as evidenced by higher GFP, in hearing-impaired individuals when compared to those with normal hearing, although the hearing-impaired show a decrease of processing effort after repeated stimulus exposure. In addition, our findings indicate that the acclimatization to a new hearing aid algorithm may take several weeks.

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Auditory perceptual efficacy of nonlinear frequency compression used in hearing aids: A review

et al. 2017

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Many patients with sensorineural hearing loss have a precipitous high-frequency loss with relatively good thresholds in the low frequencies. This present paper briefly introduces and compares the basic principles of four types of frequency lowering algorithms with emphasis on nonlinear frequency compression (NLFC). A review of the effects of the NLFC algorithm on speech and music perception and sound quality appraisal is then provided. For vowel perception, it seems that the benefits provided by NLFC are limited, which are probably related to the parameter settings of the compression. For consonant perception, several studies have shown that NLFC provides improved perception of high-frequency consonants such as /s/ and /z/. However, a few other studies have demonstrated negative results in consonant perception. In terms of sentence recognition, persistent use of NLFC might provide improved performance. Compared to the conventional processing, NLFC does not alter the speech sound quality appraisal and music perception as long as the compression setting is not too aggressive. In the subsequent section, the relevant factors with regard to NLFC settings, time-course of acclimatization, listener characteristics, and perceptual tasks are discussed. Although the literature shows mixed results on the perceptual efficacy of NLFC, this technique improved certain aspects of speech understanding in certain hearing-impaired listeners. Little research is available on speech perception outcomes in languages other than English. More clinical data are needed to verify the perceptual efficacy of NLFC in patients with precipitous high-frequency hearing loss. Such knowledge will help guide clinical rehabilitation of those patients.

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Nonlinear frequency compression: Influence of start frequency and input bandwidth on consonant and vowel recognition

Cited by 23 publications

References 46 publications

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

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

The impact of hearing aids and age-related hearing loss on auditory plasticity across three months – An electrical neuroimaging study

Auditory perceptual efficacy of nonlinear frequency compression used in hearing aids: A review

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