Speech Intelligibility Benefits of Hearing Aids at Various Input Levels

2015 ◽  
Vol 26 (03) ◽  
pp. 275-288 ◽  
Author(s):  
Francis Kuk ◽  
Chi-chuen Lau ◽  
Petri Korhonen ◽  
Bryan Crose
Keyword(s):  
Speech Perception ◽  
Hearing Aids ◽  
Repeated Measures ◽  
Speech Intelligibility ◽  
Digital Signal ◽  
High Noise ◽  
Repeated Measures Design ◽  
Speech In Noise ◽  
Directional Microphone ◽  
Subjective Preference

Background: Although the benefits of hearing aids are generally recognized for soft- and conversational-level sounds, most studies have reported negative benefits (i.e., poorer aided than unaided performance) at high noise inputs. Advances in digital signal processing such as compression, noise reduction, and directional microphone could improve speech perception at high input levels. This could alter our view on the efficacy of hearing aids in loud, noisy situations. Purpose: The current study compared the aided versus the unaided speech intelligibility performance of hearing-impaired (HI) listeners at various input levels (from 50–100 dB SPL) and signal-to-noise ratios (SNRs; quiet, +6, +3, and –3 dB) in order to document the benefits of modern hearing aids. In addition, subjective preference between aided and unaided sounds (speech and music) at various input levels was also compared. Research Design: The experiment used a factorial repeated-measures design. Study Sample: A total of 10 HI adults with symmetrical moderate to severe hearing losses served as test participants. In addition, speech intelligibility scores of five normal-hearing (NH) listeners were also measured for comparison. Intervention: Speech perception was studied at 50 and 65 dB SPL input levels in quiet and also in noise at levels of 65, 85, and 100 dB SPL with SNRs of +6, +3, and –3 dB. This was done for all participants (HI and NH). In addition, the HI participants compared subjective preference between the aided and unaided presentations of speech and music stimuli at 50, 65, 85, and 100 dB SPL in quiet. Data Collection and Analysis: The data were analyzed with repeated-measures analysis of variance. Results: The results showed a decrease in aided benefits as input levels increased. However, even at the two highest input levels (i.e., 85 and 100 dB SPL), aided speech scores were still higher than the unaided speech scores. Furthermore, NH listeners and HI listeners in the aided condition showed stable speech-in-noise performance between 65 and 100 dB SPL input levels, except that the absolute performance of the NH listeners was higher than that of the HI listeners. Subjective preference for the unaided sounds versus the aided sounds increased as input level increased, with a crossover intensity at approximately 75 dB SPL for speech and 80 dB SPL for music. Conclusions: The results supported the hypothesis that the study hearing aid can provide aided speech-in-noise benefit at very high noise inputs in a controlled environment.

Effects of a Transient Noise Reduction Algorithm on Speech Understanding, Subjective Preference, and Preferred Gain

2013 ◽  
Vol 24 (09) ◽  
pp. 845-858 ◽  
Author(s):  
Petri Korhonen ◽  
Francis Kuk ◽  
Chi Lau ◽  
Denise Keenan ◽  
Jennifer Schumacher ◽  
...  
Keyword(s):  
Noise Reduction ◽  
Hearing Aids ◽  
Repeated Measures ◽  
Speech Intelligibility ◽  
Repeated Measures Design ◽  
Subjective Preference ◽  
Listening Environments ◽  
Speech Identification ◽  
Noise Reduction Algorithm ◽  
Phoneme Identification

Background: Today's compression hearing aids with noise reduction systems may not manage transient noises effectively because of the short duration of these sounds compared to the onset times of the compressors and/or noise reduction algorithms. Purpose: The current study was designed to evaluate the effect of a transient noise reduction (TNR) algorithm on listening comfort, speech intelligibility in quiet, and preferred wearer gain in the presence of transients. Research Design: A single-blinded, repeated-measures design was used. Study Sample: Thirteen experienced hearing aid users with bilaterally symmetrical (≤7.5 dB) sensorineural hearing loss participated in the study. Results: Speech identification in quiet (no transient noise) was identical between the TNR On and the TNR Off conditions. The participants showed subjective preference for the TNR algorithm when “comfortable listening” was used as the criterion. Participants preferred less gain than the default prescription in the presence of transient noise sounds. However, the preferred gain was 2.9 dB higher when the TNR was activated than when it was deactivated. This translated to 12.1% improvement in phoneme identification over the TNR Off condition for soft speech. Conclusions: This study demonstrated that the use of the TNR algorithm would not negatively affect speech identification. The results also suggested that this algorithm may improve listening comfort in the presence of transient noise sounds and ensure consistent use of prescribed gain. Such an algorithm may ensure more consistent audibility across listening environments.

scholarly journals Children's Perception of Speech Produced in a Two-Talker Background

2014 ◽  
Vol 57 (1) ◽  
pp. 327-337 ◽  
Author(s):  
Mallory Baker ◽  
Emily Buss ◽  
Adam Jacks ◽  
Crystal Taylor ◽  
Lori J. Leibold
Keyword(s):  
Speech Perception ◽  
Word Recognition ◽  
Repeated Measures ◽  
Signal To Noise Ratio ◽  
Age Groups ◽  
Recognition Task ◽  
Monosyllabic Word ◽  
Repeated Measures Design ◽  
Speech In Noise ◽  
Open Set

Purpose This study evaluated the degree to which children benefit from the acoustic modifications made by talkers when they produce speech in noise. Method A repeated measures design compared the speech perception performance of children (5–11 years) and adults in a 2-talker masker. Target speech was produced in a 2-talker background or in quiet. In Experiment 1, recognition with the 2 target sets was assessed using an adaptive spondee identification procedure. In Experiment 2, the benefit of speech produced in a 2-talker background was assessed using an open-set, monosyllabic word recognition task at a fixed signal-to-noise ratio (SNR). Results Children performed more poorly than adults, regardless of whether the target speech was produced in quiet or in a 2-talker background. A small improvement in the SNR required to identify spondees was observed for both children and adults using speech produced in a 2-talker background (Experiment 1). Similarly, average open-set word recognition scores were 11 percentage points higher for both age groups using speech produced in a 2-talker background compared with quiet (Experiment 2). Conclusion The results indicate that children can use the acoustic modifications of speech produced in a 2-talker background to improve masked speech perception, as previously demonstrated for adults.

Quantification of Directional Benefit across Different Polar Response Patterns

2004 ◽  
Vol 15 (09) ◽  
pp. 649-659 ◽  
Author(s):  
Ruth A. Bentler ◽  
Jessica L.M. Egge ◽  
Jill L. Tubbs ◽  
Andrew B. Dittberner ◽  
Gregory A. Flamme
Keyword(s):  
Speech Perception ◽  
Hearing Aids ◽  
Hearing Aid ◽  
Sound Quality ◽  
Response Patterns ◽  
Directional Microphones ◽  
Speech In Noise ◽  
Directional Microphone ◽  
Hearing In Noise ◽  
The Right

The purpose of this study was to assess the relationship between the directivity of a directional microphone hearing aid and listener performance. Hearing aids were fit bilaterally to 19 subjects with sensorineural hearing loss, and five microphone conditions were assessed: omnidirectional, cardioid, hypercardioid, supercardioid, and "monofit," wherein the left hearing aid was set to omnidirectional and the right hearing aid to hypercardioid. Speech perception performance was assessed using the Hearing in Noise Test (HINT) and the Connected Speech Test (CST). Subjects also assessed eight domains of sound quality for three stimuli (speech in quiet, speech in noise, and music). A diffuse soundfield system composed of eight loudspeakers forming the corners of a cube was used to output the background noise for the speech perception tasks and the three stimuli used for sound quality judgments. Results indicated that there were no significant differences in the HINT or CST performance, or sound quality judgments, across the four directional microphone conditions when tested in a diffuse field. Of particular interest was the monofit condition: Performance on speech perception tests was the same whether one or two directional microphones were used.

scholarly journals Effectiveness of the Directional Microphone in the ®Baha® Divino™

2010 ◽  
Vol 21 (08) ◽  
pp. 546-557 ◽  
Author(s):  
Kristi Oeding ◽  
Michael Valente ◽  
Jessica Kerckhoff
Keyword(s):  
Speech Recognition ◽  
Hearing Aids ◽  
Repeated Measures ◽  
Signal To Noise Ratio ◽  
Recognition Performance ◽  
Great Difficulty ◽  
Repeated Measures Design ◽  
Directional Microphone ◽  
Paired Samples ◽  
Speech Recognition In Noise

Background: Patients with unilateral sensorineural hearing loss (USNHL) experience great difficulty listening to speech in noisy environments. A directional microphone (DM) could potentially improve speech recognition in this difficult listening environment. It is well known that DMs in behind-the-ear (BTE) and custom hearing aids can provide a greater signal-to-noise ratio (SNR) in comparison to an omnidirectional microphone (OM) to improve speech recognition in noise for persons with hearing impairment. Studies examining the DM in bone anchored auditory osseointegrated implants (Baha), however, have been mixed, with little to no benefit reported for the DM compared to an OM. Purpose: The primary purpose of this study was to determine if there are statistically significant differences in the mean reception threshold for sentences (RTS in dB) in noise between the OM and DM in the Baha® Divino™. The RTS of these two microphone modes was measured utilizing two loudspeaker arrays (speech from 0° and noise from 180° or a diffuse eight-loudspeaker array) and with the better ear open or closed with an earmold impression and noise attenuating earmuff. Subjective benefit was assessed using the Abbreviated Profile of Hearing Aid Benefit (APHAB) to compare unaided and aided (Divino OM and DM combined) problem scores. Research Design: A repeated measures design was utilized, with each subject counterbalanced to each of the eight treatment levels for three independent variables: (1) microphone (OM and DM), (2) loudspeaker array (180° and diffuse), and (3) better ear (open and closed). Study Sample: Sixteen subjects with USNHL currently utilizing the Baha were recruited from Washington University's Center for Advanced Medicine and the surrounding area. Data Collection and Analysis: Subjects were tested at the initial visit if they entered the study wearing the Divino or after at least four weeks of acclimatization to a loaner Divino. The RTS was determined utilizing Hearing in Noise Test (HINT) sentences in the R-Space™ system, and subjective benefit was determined utilizing the APHAB. A three-way repeated measures analysis of variance (ANOVA) and a paired samples t-test were utilized to analyze results of the HINT and APHAB, respectively. Results: Results revealed statistically significant differences within microphone (p < 0.001; directional advantage of 3.2 dB), loudspeaker array (p = 0.046; 180° advantage of 1.1 dB), and better ear conditions (p < 0.001; open ear advantage of 4.9 dB). Results from the APHAB revealed statistically and clinically significant benefit for the Divino relative to unaided on the subscales of Ease of Communication (EC) (p = 0.037), Background Noise (BN) (p < 0.001), and Reverberation (RV) (p = 0.005). Conclusions: The Divino's DM provides a statistically significant improvement in speech recognition in noise compared to the OM for subjects with USNHL. Therefore, it is recommended that audiologists consider selecting a Baha with a DM to provide improved speech recognition performance in noisy listening environments.

Evaluation of a Pinna Compensation Algorithm for Sound Localization and Speech Perception in Noise

2013 ◽  
Vol 22 (1) ◽  
pp. 84-93 ◽  
Author(s):  
Francis Kuk ◽  
Petri Korhonen ◽  
Chi Lau ◽  
Denise Keenan ◽  
Magnus Norgaard
Keyword(s):  
Repeated Measures ◽  
Speech Intelligibility ◽  
Horizontal Plane ◽  
Signal To Noise Ratio ◽  
Hearing Aid ◽  
Noise Performance ◽  
Repeated Measures Design ◽  
Speech In Noise ◽  
Pc Algorithm ◽  
Localization Performance

Purpose This study was designed to evaluate the effect of a pinna compensation (PC) algorithm on localization performance in the horizontal plane and speech intelligibility in noise. Method Nine and 18 experienced hearing aid users with bilaterally symmetrical sensorineural hearing loss participated in the localization study and the speech-in-noise study, respectively. Performance was evaluated unaided, aided with a behind-the-ear (BTE) hearing aid with an omnidirectional microphone (Omni), and aided with the same hearing aid with the PC algorithm (Omni+PC). Localization performance was measured using 12 loudspeakers spaced 30° apart on a horizontal plane. Speech-in-noise performance was measured with speech presented from 0° or 180°. A single-blinded, repeated measures design was used. Results Significant improvement in localization accuracy was found when comparing the Omni+PC condition to the Omni condition. Also, the Omni+PC condition improved the signal-to-noise ratio by 2.4 dB when compared to the Omni condition when speech was presented from the front in a diffuse noise background. Conclusion Use of the PC algorithm improved localization on the horizontal plane and speech-in-noise performance. These results support use of the PC algorithm in BTE hearing aid fittings.

scholarly journals Evaluation of the Efficacy of a Dual Variable Speed Compressor over a Single Fixed Speed Compressor

2019 ◽  
Vol 30 (07) ◽  
pp. 590-606 ◽  
Author(s):  
Francis Kuk ◽  
Chris Slugocki ◽  
Petri Korhonen ◽  
Eric Seper ◽  
Ole Hau
Keyword(s):  
Hearing Aids ◽  
Repeated Measures ◽  
Speech Intelligibility ◽  
Signal To Noise Ratio ◽  
Recall Performance ◽  
Variable Speed ◽  
Listening Effort ◽  
Subjective Report ◽  
Repeated Measures Design ◽  
Compression Speed

AbstractIt has been suggested that hearing-impaired listeners with a good working memory (WM) should be fitted with a compression system using short time constants (i.e., fast-acting compression [FAC]), whereas those with a poorer WM should be fitted with a longer time constant (i.e., slow-acting compression [SAC]). However, commercial hearing aids (HAs) seldom use a fixed speed of compression.The performance of a variable speed compression (VSC) system relative to a fixed speed compressor (FAC and SAC) on measures of speech intelligibility, recall, and subjective report of listening effort and tolerable time was evaluated. The potential interaction with the listeners’ WM capacity (WMC) was also examined.A double-blinded, repeated measures design.Seventeen HA wearers (16 with greater than one year HA experience) with a bilaterally symmetrical, mild to moderately severe sensorineural hearing loss participated in the study.Participants wore the study HAs at three compression speeds (FAC, SAC, and VSC). Each listener was evaluated on the Office of Research in Clinical Amplification-nonsense syllable test (NST) at 50 dB SPL (signal-to-noise ratio [SNR] = +15 dB), 65 dB SPL (SNR = +5 dB), 80 dB SPL (SNR = 0 dB), and a split (80 dB SPL–50 dB SPL) condition. Listeners were also evaluated on a Repeat Recall Test (RRT), where they had to repeat six short sentences (both high- and low-context sentences) after each was presented. Listeners recalled target words in all six sentences after they were presented. They also rated their listening effort and the amount of time they would tolerate listening under the specific condition. RRT sentences were presented at 75 dB SPL in quiet, as well as SNR = 0, 5, 10, and 15 dB. A Reading Span Test (RST) was also administered to assess listeners’ WMC. Analysis of variance using RST scores as a covariate was used to examine differences in listener performance among compressor speeds.Listener performance on the NST was similar among all three compression speeds at 50, 65, and 80 dB SPL. Performance with FAC was significantly better than SAC for the split condition; however, performance did not differ between FAC and VSC or between SAC and VSC. Performance on the NST was not affected by listeners’ RST scores. On the RRT, there was no effect of compressor speed on measures of repeat, recall, listening effort, and tolerable time. However, VSC resulted in significantly lower (better) speech reception threshold at the 85% correct recognition criterion (SRT85) than FAC and SAC. Listener RST scores significantly affected recall performance on the RRT but did not affect SRT85, repeat, listening effort, or tolerable time.These results suggest that the VSC, FAC, and SAC yield similar performance in most but not all test conditions. FAC outperforms SAC, where the stimulus levels change abruptly (i.e., split condition). The VSC yields a lower SRT85 than a fixed compression speed at a moderately high level with a favorable SNR. There is no interaction between compression speed and the participants’ WMC.

scholarly journals Upgrade to Nucleus® 6 in Previous Generation Cochlear™ Sound Processor Recipients

2018 ◽  
Vol 29 (09) ◽  
pp. 802-813 ◽  
Author(s):  
Allison Biever ◽  
Jan Gilden ◽  
Teresa Zwolan ◽  
Megan Mears ◽  
Anne Beiter
Keyword(s):  
Speech Perception ◽  
User Satisfaction ◽  
Repeated Measures ◽  
Background Noise ◽  
First Generation ◽  
Repeated Measures Design ◽  
Signal Processing Algorithms ◽  
Final Speech ◽  
New Algorithms ◽  
Sound Processor

AbstractThe Nucleus® 6 sound processor is now compatible with the Nucleus® 22 (CI22M)—Cochlear’s first generation cochlear implant. The Nucleus 6 offers three new signal processing algorithms that purportedly facilitate improved hearing in background noise.These studies were designed to evaluate listening performance and user satisfaction with the Nucleus 6 sound processor.The research design was a prospective, single-participant, repeated measures designA group of 80 participants implanted with various Nucleus internal implant devices (CI22M, CI24M, Freedom® CI24RE, CI422, and CI512) were recruited from a total of six North American sites.Participants had their external sound processor upgraded to the Nucleus 6 sound processor. Final speech perception testing in noise and subjective questionnaires were completed after four or 12 weeks of take-home use with the Nucleus 6.Speech perception testing in noise showed significant improvement and participants reported increased satisfaction with the Nucleus 6.These studies demonstrated the benefit of the new algorithms in the Nucleus 6 over previous generations of sound processors.

scholarly journals The Effect of Binaural Beamforming Technology on Speech Intelligibility in Bimodal Cochlear Implant Recipients

2018 ◽  
Vol 23 (1) ◽  
pp. 32-38 ◽  
Author(s):  
Jantien L. Vroegop ◽  
Nienke C. Homans ◽  
André Goedegebure ◽  
J. Gertjan Dingemanse ◽  
Teun van Immerzeel ◽  
...  
Keyword(s):  
Cochlear Implant ◽  
Repeated Measures ◽  
Speech Intelligibility ◽  
Real Life ◽  
Speech Comprehension ◽  
Noise Sources ◽  
Additional Advantage ◽  
Listening Condition ◽  
Repeated Measures Design ◽  
Speech Reception Thresholds

Although the benefit of bimodal listening in cochlear implant users has been agreed on, speech comprehension remains a challenge in acoustically complex real-life environments due to reverberation and disturbing background noises. One way to additionally improve bimodal auditory performance is the use of directional microphones. The objective of this study was to investigate the effect of a binaural beamformer for bimodal cochlear implant (CI) users. This prospective study measured speech reception thresholds (SRT) in noise in a repeated-measures design that varied in listening modality for static and dynamic listening conditions. A significant improvement in SRT of 4.7 dB was found with the binaural beamformer switched on in the bimodal static listening condition. No significant improvement was found in the dynamic listening condition. We conclude that there is a clear additional advantage of the binaural beamformer in bimodal CI users for predictable/static listening conditions with frontal target speech and spatially separated noise sources.

scholarly journals Speech Perception for Adult Cochlear Implant Recipients in a Realistic Background Noise: Effectiveness of Preprocessing Strategies and External Options for Improving Speech Recognition in Noise

2010 ◽  
Vol 21 (07) ◽  
pp. 441-451 ◽  
Author(s):  
René H. Gifford ◽  
Lawrence J. Revit
Keyword(s):  
Speech Recognition ◽  
Speech Perception ◽  
Cochlear Implant ◽  
Repeated Measures ◽  
Recognition Performance ◽  
Single Subject ◽  
Repeated Measures Design ◽  
Listening Environments ◽  
Improved Performance ◽  
Listening In Noise

Background: Although cochlear implant patients are achieving increasingly higher levels of performance, speech perception in noise continues to be problematic. The newest generations of implant speech processors are equipped with preprocessing and/or external accessories that are purported to improve listening in noise. Most speech perception measures in the clinical setting, however, do not provide a close approximation to real-world listening environments. Purpose: To assess speech perception for adult cochlear implant recipients in the presence of a realistic restaurant simulation generated by an eight-loudspeaker (R-SPACE™) array in order to determine whether commercially available preprocessing strategies and/or external accessories yield improved sentence recognition in noise. Research Design: Single-subject, repeated-measures design with two groups of participants: Advanced Bionics and Cochlear Corporation recipients. Study Sample: Thirty-four subjects, ranging in age from 18 to 90 yr (mean 54.5 yr), participated in this prospective study. Fourteen subjects were Advanced Bionics recipients, and 20 subjects were Cochlear Corporation recipients. Intervention: Speech reception thresholds (SRTs) in semidiffuse restaurant noise originating from an eight-loudspeaker array were assessed with the subjects' preferred listening programs as well as with the addition of either Beam™ preprocessing (Cochlear Corporation) or the T-Mic® accessory option (Advanced Bionics). Data Collection and Analysis: In Experiment 1, adaptive SRTs with the Hearing in Noise Test sentences were obtained for all 34 subjects. For Cochlear Corporation recipients, SRTs were obtained with their preferred everyday listening program as well as with the addition of Focus preprocessing. For Advanced Bionics recipients, SRTs were obtained with the integrated behind-the-ear (BTE) mic as well as with the T-Mic. Statistical analysis using a repeated-measures analysis of variance (ANOVA) evaluated the effects of the preprocessing strategy or external accessory in reducing the SRT in noise. In addition, a standard t-test was run to evaluate effectiveness across manufacturer for improving the SRT in noise. In Experiment 2, 16 of the 20 Cochlear Corporation subjects were reassessed obtaining an SRT in noise using the manufacturer-suggested “Everyday,” “Noise,” and “Focus” preprocessing strategies. A repeated-measures ANOVA was employed to assess the effects of preprocessing. Results: The primary findings were (i) both Noise and Focus preprocessing strategies (Cochlear Corporation) significantly improved the SRT in noise as compared to Everyday preprocessing, (ii) the T-Mic accessory option (Advanced Bionics) significantly improved the SRT as compared to the BTE mic, and (iii) Focus preprocessing and the T-Mic resulted in similar degrees of improvement that were not found to be significantly different from one another. Conclusion: Options available in current cochlear implant sound processors are able to significantly improve speech understanding in a realistic, semidiffuse noise with both Cochlear Corporation and Advanced Bionics systems. For Cochlear Corporation recipients, Focus preprocessing yields the best speech-recognition performance in a complex listening environment; however, it is recommended that Noise preprocessing be used as the new default for everyday listening environments to avoid the need for switching programs throughout the day. For Advanced Bionics recipients, the T-Mic offers significantly improved performance in noise and is recommended for everyday use in all listening environments.

The Effects of Noise Reduction Technologies on the Acceptance of Background Noise

2013 ◽  
Vol 24 (08) ◽  
pp. 649-659 ◽  
Author(s):  
Kristy Jones Lowery ◽  
Patrick N. Plyler
Keyword(s):  
Noise Reduction ◽  
Hearing Aids ◽  
Repeated Measures ◽  
Background Noise ◽  
Negative Effects ◽  
Directional Microphones ◽  
Repeated Measures Design ◽  
Noise Type ◽  
Data Collection And Analysis ◽  
Speech Spectrum

Background: Directional microphones (D-Mics) and digital noise reduction (DNR) algorithms are used in hearing aids to reduce the negative effects of background noise on performance. Directional microphones attenuate sounds arriving from anywhere other than the front of the listener while DNR attenuates sounds with physical characteristics of noise. Although both noise reduction technologies are currently available in hearing aids, it is unclear if the use of these technologies in isolation or together affects acceptance of noise and/or preference for the end user when used in various types of background noise. Purpose: The purpose of the research was to determine the effects of D-Mic, DNR, or the combination of D-Mic and DNR on acceptance of noise and preference when listening in various types of background noise. Research Design: An experimental study in which subjects were exposed to a repeated measures design was utilized. Study Sample: Thirty adult listeners with mild sloping to moderately severe sensorineural hearing loss participated (mean age 67 yr). Data Collection and Analysis: Acceptable noise levels (ANLs) were obtained using no noise reduction technologies, D-Mic only, DNR only, and the combination of the two technologies (Combo) for three different background noises (single-talker speech, speech-shaped noise, and multitalker babble) for each listener. In addition, preference rankings of the noise reduction technologies were obtained within each background noise (1 = best, 3 = worst). Results: ANL values were significantly better for each noise reduction technology than baseline; and benefit increased significantly from DNR to D-Mic to Combo. Listeners with higher (worse) baseline ANLs received more benefit from noise reduction technologies than listeners with lower (better) baseline ANLs. Neither ANL values nor ANL benefit values were significantly affected by background noise type; however, ANL benefit with D-Mic and Combo was similar when speech-like noise was present while ANL benefit was greatest for Combo when speech spectrum noise was present. Listeners preferred the hearing aid settings that resulted in the best ANL value. Conclusion: Noise reduction technologies improved ANL for each noise type, and the amount of improvement was related to the baseline ANL value. Improving an ANL with noise reduction technologies is noticeable to listeners, at least when examined in this laboratory setting, and listeners prefer noise reduction technologies that improved their ability to accept noise.

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