Acceptable Noise Levels and Preferred Signal-to-noise Ratios for Speech and Music.

OBJECTIVES: The objective of this study was to evaluate the influence of music versus speech on a listener's signal-to-noise ratio (SNR) preferences when listening in a noise background. SNR preferences were quantified using acceptable noise level (ANL) and preferred SNR metrics. The measurement paradigm for ANL allows the listener to adjust the level of background noise while listening to the target at their most comfortable loudness level. A higher ANL indicates less tolerance for noise and a lower ANL indicates high tolerance for noise. The preferred SNR is simply the SNR the listener prefers when attending to a target in a fixed-amount (level) of background noise. In contrast to the ANL, the listener does not have control over the noise. Rather, they are only able to manipulate the target level. The first aim of the study was to determine if listeners' tolerances for noise, quantified using the ANL, when listening to music is different from that when listening to speech. The second aim of the study was to determine if listeners' tolerances for noise, quantified using their preferred SNR, when listening to music is different from that when listening to speech. The third aim of the study was to quantify the relationship between ANL and preferred SNR. DESIGN: Ninety-nine normal-hearing, native-English speakers participated in this study. The ANL and preferred SNR were measured for speech and music targets. Music targets included two variations (with lyrics and without lyrics) of the song "Rocky Top." Measurements were made in the sound field at 0° azimuth, 1.5 m from a loud speaker. For both ANL and preferred SNR, targets were presented in 12-talker babble noise. The level of the noise was adjusted by the listener during ANL measurement but was fixed in level during the preferred SNR measurement (75 dB A). Repeated-measures analysis of variance was performed to identify any significant effect of target on the ANL and preferred SNR. Correlation analysis was performed to evaluate the relationship between ANL and preferred SNR. RESULTS: Findings demonstrate a significant effect of target on ANL and preferred SNR. ANLs were highest for speech (mean = 7.2 dB), followed by music with lyrics (6.1 dB), and music without lyrics (2.5 dB). Preferred SNRs were highest for music with lyrics (mean = 2.3 dB), followed by speech (1.2 dB), and music without lyrics (-0.1 dB). A listener's ANL for a given target was strongly correlated with their ANL for a different target (the same was true for preferred SNR); however, ANL for a given target was not a statistically significant predictor of preferred SNR for the same target. CONCLUSIONS: When listening in a background of noise, the listener's tolerance for noise depends on the target to which they are attending, whether music or speech. This dependence is especially evident for ANL measures, and less so for preferred SNR measures. Despite differences in ANL and preferred SNR across targets, a listener's ANL and preferred SNR for one target predicts their ANL and preferred SNR, respectively, for a different target. The lack of correlation between ANL and preferred SNR suggests different mechanisms underly these listener-preference metrics.

Frontotemporal activation differs between perception of simulated cochlear implant speech and speech in background noise: An image-based fNIRS study.

In this study we used functional near-infrared spectroscopy (fNIRS) to investigate neural responses in normal-hearing adults as a function of speech recognition accuracy, intelligibility of the speech stimulus, and the manner in which speech is distorted. Participants listened to sentences and reported aloud what they heard. Speech quality was distorted artificially by vocoding (simulated cochlear implant speech) or naturally by adding background noise. Each type of distortion included high and low-intelligibility conditions. Sentences in quiet were used as baseline comparison. fNIRS data were analyzed using a newly developed image reconstruction approach. First, elevated cortical responses in the middle temporal gyrus (MTG) and middle frontal gyrus (MFG) were associated with speech recognition during the low-intelligibility conditions. Second, activation in the MTG was associated with recognition of vocoded speech with low intelligibility, whereas MFG activity was largely driven by recognition of speech in background noise, suggesting that the cortical response varies as a function of distortion type. Lastly, an accuracy effect in the MFG demonstrated significantly higher activation during correct perception relative to incorrect perception of speech. These results suggest that normal-hearing adults (i.e., untrained listeners of vocoded stimuli) do not exploit the same attentional mechanisms of the frontal cortex used to resolve naturally degraded speech and may instead rely on segmental and phonetic analyses in the temporal lobe to discriminate vocoded speech.

The Use of Static and Dynamic Cues for Vowel Identification by Children Wearing Hearing Aids or Cochlear Implants.

OBJECTIVE: To examine vowel perception based on dynamic formant transition and/or static formant pattern cues in children with hearing loss while using their hearing aids or cochlear implants. We predicted that the sensorineural hearing loss would degrade formant transitions more than static formant patterns, and that shortening the duration of cues would cause more difficulty for vowel identification for these children than for their normal-hearing peers. DESIGN: A repeated-measures, between-group design was used. Children 4 to 9 years of age from a university hearing services clinic who were fit for hearing aids (13 children) or who wore cochlear implants (10 children) participated. Chronologically age-matched children with normal hearing served as controls (23 children). Stimuli included three naturally produced syllables (/ba/, /bi/, and /bu/), which were presented either in their entirety or segmented to isolate the formant transition or the vowel static formant center. The stimuli were presented to listeners via loudspeaker in the sound field. Aided participants wore their own devices and listened with their everyday settings. Participants chose the vowel presented by selecting from corresponding pictures on a computer screen. RESULTS: Children with hearing loss were less able to use shortened transition or shortened vowel centers to identify vowels as compared to their normal-hearing peers. Whole syllable and initial transition yielded better identification performance than the vowel center for /ɑ/, but not for /i/ or /u/. CONCLUSIONS: The children with hearing loss may require a longer time window than children with normal hearing to integrate vowel cues over time because of altered peripheral encoding in spectrotemporal domains. Clinical implications include cognizance of the importance of vowel perception when developing habilitative programs for children with hearing loss.

Mental tasking and rotary Chair-Induced vestibular nystagmus utilizing Video-Oculography.

Objective: To investigate whether the use of mental tasking, when compared to no mental task, affects measurement of nystagmus response with regard to gain, phase & symmetry, and artefact when utilising video-oculography (VOG) as the measurement technique in rotary chair testing (RCT).Design: A within-subject repeated-measures design was utilised.Study samples: Seventeen (17) healthy adults were evaluated (age 22-25 years). Each participant underwent slow harmonic acceleration (SHA) testing for 0.01, 0.02, 0.04, 0.08, and 0.16 Hz using RCT at two separate counterbalanced visits. At one visit mental tasking was utilised while the other visit did not utilise mental tasking. The following outcomes were measured for each visit: gain, phase, symmetry, and artefact.Results: No significant difference between the tasking conditions with regard to gain, phase, symmetry, or artefact. Significant frequency affects were noted, as expected, for gain, phase, and artefact. Analysis of individual subject data did, however, describe significant effects of tasking with regard to gain, phase, symmetry, and artefact.Conclusion: These results suggest that the use of mental tasking during RCT using VOG had no significant group effect on SHA gain, phase, symmetry, and artefact. However, individual subject effects were observed indicating variability in the effects of mental tasking during RCT.

The effects of noise reduction technologies on the acceptance of background noise.

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.

Comparison of multichannel wide dynamic range compression and ChannelFree processing in open canal hearing instruments.

BACKGROUND: Multichannel wide dynamic range compression (WDRC) and ChannelFree processing have similar goals yet differ significantly in terms of signal processing. Multichannel WDRC devices divide the input signal into separate frequency bands; a separate level is determined within each frequency band; and compression in each band is based on the level within each band. ChannelFree processing detects the wideband level, and gain adjustments are based on the wideband signal level and adjusted up to 20,000 times per second. Although both signal processing strategies are currently available in hearing aids, it is unclear if differences in these signal processing strategies affect the performance and/or preference of the end user. PURPOSE: The purpose of the research was to determine the effects of multichannel wide dynamic range compression and ChannelFree processing on performance and/or preference of listeners using open-canal hearing instruments. RESEARCH DESIGN: An experimental study in which subjects were exposed to a repeated measures design was utilized. STUDY SAMPLE: Fourteen adult listeners with mild sloping to moderately severe sensorineural hearing loss participated (mean age 67 yr). DATA COLLECTION AND ANALYSIS: Participants completed two 5 wk trial periods for each signal processing strategy. Probe microphone, behavioral and subjective measures were conducted unaided and aided at the end of each trial period. RESULTS: Behavioral and subjective results for both signal processing strategies were significantly better than unaided results; however, behavioral and subjective results were not significantly different between the signal processing strategies. CONCLUSIONS: Multichannel WDRC and ChannelFree processing are both effective signal processing strategies that provide significant benefit for hearing instrument users. Overall preference between the strategies may be related to the degree of hearing loss of the user, high-frequency in-situ levels, and/or acceptance of background noise.

Effectiveness of Television Streaming on Hearing Aid User Performance and Satisfaction in Quiet and in Noise.

PURPOSE: The purpose of this study was to determine the effectiveness of television (TV) streaming on hearing aid user performance and satisfaction in quiet and in noise. METHOD: Twenty experienced hearing aid users were evaluated in quiet and in noise (5 dB SNR) under three hearing aid conditions: hearing aids, streaming with hearing aid microphones attenuated by 6 dB, and streaming with hearing aid microphones muted. The audiovisual Connected Speech Test served as the signal, and the ipsilateral competing message from the Synthetic Sentence Identification-Ipsilateral Competing Message (SSI-ICM) served as the noise. Measures of speech understanding, satisfaction with sound quality and clarity, and preference were obtained. RESULTS: Speech understanding was significantly better in quiet than in noise, and streaming improved performance in noise when the hearing aid microphones were muted. Sound quality satisfaction was significantly better in quiet than in noise but was not impacted significantly by the hearing aid settings. Speech clarity satisfaction was significantly better in quiet than in noise, and streaming improved satisfaction in noise when the hearing aid microphones were muted. More participants preferred streaming with the microphones muted in quiet, in noise, and overall; however, results did not reach statistical significance. CONCLUSIONS: Hearing aid users did not benefit from TV streaming with the microphones attenuated or muted when listening in quiet. TV streaming was more beneficial to hearing aid users when listening in noise with the microphones muted. Hearing aid users should be counseled on the impact of the hearing aid microphone settings when using a TV streamer, particularly in noise.

Effect of Sound Source Location and Spatial Hearing on the Vestibulo-Ocular Reflex.

BACKGROUND: There have been conflicting results on the effect of auditory stimulation on the vestibulo-ocular reflex (VOR) with some studies indicating suppression, enhancement, or no effect. No studies to date have assessed the effect of sound source location on VOR gain or the relationship between spatial hearing ability and VOR gain. PURPOSE: The purpose of the present study was to determine if VOR gain was affected by moving the location of the sound source within participants and to determine if these effects were related to spatial hearing ability. RESEARCH DESIGN: A between subjects repeated measures experimental design was utilized. STUDY SAMPLE: Two groups of participants (adult and child) with normal otologic, vestibular, and neurologic function. 22 adults (20 female and 2 male; average age = 23 years) and 16 children (9 female and 7 male; average age = 7.5 years) were included in data analysis. DATA COLLECTION AND ANALYSIS: VOR gain was measured using rotational chair stimulation in the following auditory conditions: silent, insert earphones, external loudspeaker at 0° azimuth rotating with participant, and external stationary speaker. Localization ability was measured using root mean square (RMS) error. RESULTS: Results indicated a significant effect for sound source location on VOR gain and VOR difference gain in both groups. RMS error was positively correlated for the moving and fixed sound source locations for both adults and children. CONCLUSION: VOR gain was significantly affected by location of the sound source. Findings suggest the presence and location of an auditory stimulus during rotational testing can alter results during the assessment.

Effect of Hearing Aid Technology Level on New Hearing Aid Users.

BACKGROUND: Hearing aid manufacturers offer several different levels of technology that vary in sophistication and cost. It would stand to reason that higher technology hearing aids would provide greater benefit in the daily life of the user; however, research does not support this assumption for all users. Recent research in experienced hearing aid users indicated noise acceptance and satisfaction for speech in a large group were significantly improved when using the premium devices and suggested noise acceptance may be useful when comparing hearing aid technology levels. PURPOSE: The purpose of this study was to determine the effect of hearing aid technology level on listener outcome measures for new hearing aid users. RESEARCH DESIGN: A repeated measures, single-blinded research design was utilized. STUDY SAMPLE: Twenty-four adults with no previous hearing aid experience were recruited using flyers posted at the University of Tennessee Audiology Clinic and on social media (19 males, 5 females). The average age of the participants was 61 years (48-81 years). DATA COLLECTION AND ANALYSIS: Participants completed two, 4-week trial periods using Unitron T Moxi Fit FLEX:TRIAL devices programmed with basic or premium technology. Following each trial, laboratory evaluations were conducted using the QuickSIN, Hearing in Noise Test (HINT), and the Acceptable Noise Level (ANL). Subjective data was obtained using the Speech, Spatial, and Qualities of Hearing Short Form, satisfaction ratings, and preference. Data was analyzed using one-way repeated-measures analysis of variance. RESULTS: Speech perception results did not reveal significant differences between technology level on the HINT or QuickSIN; however, ANL was significantly improved for the premium devices. Subjective results revealed significantly improved satisfaction for speech in a large group and overall preference when using premium technology. CONCLUSION: Group data revealed similar outcomes between technology levels on most measures; however, noise acceptance, satisfaction for speech in a large group, and overall preference were significantly improved when using the premium devices. Individual characteristics such as noise acceptance, age, and degree of hearing loss may be useful when comparing hearing aid technology levels for new hearing aid users.

Development and evaluation of the Mandarin speech signal content on the acceptable noise level test in listeners with normal hearing in mainland China.

OBJECTIVE: To develop and evaluate the Mandarin speech signal content on the acceptable noise level (ANL) test in listeners with normal hearing in mainland China. DESIGN: The Mandarin ANL tests were conducted using three different sets of Mandarin running speech materials which were chosen from textbooks for primary school, secondary school, and high school, respectively. For each discourse, two ANL measurements were obtained and averaged for each experimental condition using ANL test procedures. STUDY SAMPLE: Thirty-one normal-hearing listeners participated in this study. RESULTS: There were significant differences for ANLs among the normal-hearing listeners, but no differences were found for MCLs and ANLs for the three sets of test materials. The Pearson correlations suggested significant correlations between MCL and ANL among the three test materials; also the results showed that the correlation coefficient between MCL-ANL of the primary material was much better than other two materials. CONCLUSIONS: (1) The contents of different Mandarin running speeches may not affect the acceptable noise level in Mandarin normal-hearing listeners; (2) The running speech selected from the primary school ought to be used as the Mandarin acceptable noise level test material to evaluate the outcomes of hearing aid fitting.

Effects of speech signal content and speaker gender on acceptance of noise in listeners with normal hearing.

OBJECTIVE: The purpose of this research was to determine if the content and/or speaker gender of a running speech sample affected the acceptance of background noise within a participant. DESIGN: A male and a female recording of the Arizona Travelogue (Cosmos Inc.) and the ipsilateral competing message (ICM) from the synthetic sentence identification with ICM were created and used as the experimental speech signals. Two acceptable noise level measurements were obtained and averaged for each condition. Twenty-one participants rated interest level in the speech sample for each condition. STUDY SAMPLE: Forty-three listeners with normal hearing participated. RESULTS: Interest level was significantly greater for the ICM than the Arizona Travelogue speech samples, and was significantly greater for female samples. Neither the content of the sample nor the gender of the speaker significantly affected the most comfortable level or the acceptable noise level. CONCLUSIONS: Findings suggest that the acceptable noise level can be measured using various types of speech signals for normal-hearing listeners.

Effect of Hearing Aid Technology Level and Individual Characteristics on Listener Outcome Measures.

Purpose The purpose of the study was to determine the effect of hearing aid technology level on listener outcome measures. In addition, we aimed to determine if individual characteristics such as noise acceptance and the demands of the listening environment impacted performance and preference. Method A repeated-measures, single-blinded research design was utilized. Twenty-four adults recruited by mail from The University of Tennessee Health Science Center Audiology Clinic participated in this experiment (15 men and nine women). Participants completed two 2-week trial periods using Unitron T Moxi Fit FLEX:TRIAL devices programmed as basic or premium technology levels. A data-logging feature, Log It All (LIA), quantified the demands of the listening environment. At the end of each trial, outcome measures were obtained using Pascoe's High-Frequency Word List, the Hearing in Noise Test, the Quick Speech-in-Noise Test, the Acceptable Noise Level (ANL), the Speech, Spatial and Qualities of Hearing short form, satisfaction ratings, and preference. Results Results for ANL, satisfaction in large groups, and LIA total coverage were significantly improved for the premium devices. Participants who preferred the premium devices received significant improvement with premium devices on the ANL and the speech in small group and speech in large group satisfaction ratings, whereas participants who preferred the basic devices did not receive significant improvement with premium devices on any outcome measure. Participants in more demanding listening environments received significant improvement with premium devices on the ANL, whereas participants in less demanding listening environments did not receive significant improvement with premium devices on any outcome measure. Conclusions Group data revealed similar outcomes between technology levels on most measures; however, noise acceptance and satisfaction for speech in a large group were significantly improved when using the premium devices. Individual characteristics such as noise acceptance and listening demands may be useful when comparing hearing aid technology levels for a given patient.

Vestibular Evoked Myogenic Potentials and Postural Control in Adults with Age-Related Hearing Loss.

BACKGROUND: Age-related changes to auditory function have been attributed to, through histopathological study, specific degradation of the sensory, supporting, and afferent structures of the cochlea. Similar to age-related hearing loss (ARHL), age-related changes to the vestibular sensory and supporting structures with specific degeneration of the saccule, utricle, otoconia, primary vestibular afferents have also been noted. Significant decreases in postural control with age are also well-documented in the literature attributed to multifactorial changes in function. PURPOSE: The purpose of this study is to further evaluate the association of ARHL and saccule/utricle function as measured by VEMPs and postural control measures. STUDY SAMPLE: Audiologic, vestibular and postural control results from 34 participants were analyzed. The age range was from 50 to 70 years old with 16 males and 18 females. Group 1 consisted of 33 ears from participants age 50-70 with normal hearing with average age of 60.8 years (sd 6.287 years) and an average speech-frequency PTA of 14.8 dB HL. Group 2 consisted of 27 ears from participants age 50-70 years with ARHL and an average age of 62.9 years (sd 4.984 years) with an average speech-frequency PTA of 39.9 dB HL. DATA COLLECTION AND ANALYSIS: Independent samples t-tests were used to assess group mean differences for dependent variables. The independent variable was group with 2 levels (normal hearing, ARHL). The dependent variables were cVEMP P1/N1 Amplitude, cVEMP P1 Latency, cVEMP N1 Latency, cVEMP P2 Latency, oVEMP N1/P1 Amplitude, oVEMP N1 Latency, and oVEMP P1 Latency. Additional analyses were completed using Pearson correlation to evaluate the relationship of audiometric findings to the dependent variables. RESULTS: Results indicated significantly decreased cVEMP P1/N1 amplitude and oVEMP N1/P1 amplitude adults 50-70-years of age with ARHL compared with their normal counterparts. Significant correlations were also found for audiometric results and both cVEMP and oVEMP measures. CONCLUSIONS: Overall, the results of this study describe concomitant auditory and vestibular degeneration as measured by audiometric testing and vestibular function testing involving the saccule and to a lesser degree the utricle.

Cognitive Measures and the Acceptable Noise Level.

OBJECTIVE: The aim of this study was to determine the relation between the acceptable noise level (ANL) and cognitive measures of auditory attention and working memory. DESIGN: Young adults were administered the following tests: the ANL, the Digit Span and Letter-Number Sequencing subtests of the Wechsler Adult Intelligence Scale-Fourth Edition, the Auditory Attention subtest from the Woodcock-Johnson Tests of Cognitive Abilities, the Hearing in Noise Test (HINT), and the operation span (OSPAN) test. A correlation matrix was constructed using Pearson coefficients. STUDY SAMPLE: Twenty-four young adults aged 20-29 years with normal hearing participated in the study. RESULTS: No significant relationships were found among the ANL and the different cognitive tasks, nor was there a significant relation found between the ANL and the HINT. However, significant relationships were found between individual cognitive tasks. There was a significant relation found between selective attention and the most comfortable level of presentation of a story. CONCLUSION: Selective attention may be a key cognitive function in acceptance of background noise.

The effects of receiver placement on probe microphone, performance, and subjective measures with open canal hearing instruments.

BACKGROUND: Open canal hearing instruments differ in method of sound delivery to the ear canal, distance between the microphone and the receiver, and physical size of the devices. Moreover, RITA (receiver in the aid) and RITE (receiver in the ear) hearing instruments may also differ in terms of retention and comfort as well as ease of use and care for certain individuals. What remains unclear, however, is if any or all of the abovementioned factors contribute to hearing aid outcome. PURPOSE: To determine the effect of receiver location on performance and/or preference of listeners using open canal hearing instruments. RESEARCH DESIGN: An experimental study in which subjects were exposed to a repeated measures design. STUDY SAMPLE: Twenty-five adult listeners with mild sloping to moderately severe sensorineural hearing loss (mean age 67 yr). DATA COLLECTION AND ANALYSIS: Participants completed two six-week trial periods for each device type. Probe microphone, objective, and subjective measures (quiet, noise) were conducted unaided and aided at the end of each trial period. RESULTS: Occlusion effect results were not significantly different between the RITA and RITE instruments; however, frequency range was extended in the RITE instruments, resulting in significantly greater maximum gain for the RITE instruments than the RITA instruments at 4000 and 6000 Hz. Objective performance in quiet or in noise was unaffected by receiver location. Subjective measures revealed significantly greater satisfaction ratings for the RITE than for the RITA instruments. Similarly, preference in quiet and overall preference were significantly greater for the RITE than for the RITA instruments. CONCLUSIONS: Although no occlusion differences were noted between instruments, the RITE did demonstrate a significant difference in reserve gain before feedback at 4000 and 6000 Hz. Objectively; no positive benefit was noted between unaided and aided conditions on speech recognition tests. These results suggest that such testing may not be sensitive enough to determine aided benefit with open canal instruments. However, the subjective measures (Abbreviated Profile of Hearing Aid Benefit [APHAB] and subjective ratings) did indicate aided benefit for both instruments when compared to unaided. This further suggests the clinical importance of subjective measures as a way to measure aided benefit of open-fit devices.

Relationship Between Auditory and Visual Noise Acceptance in Normal-Hearing Listeners.

BACKGROUND: Research has shown that hearing aid acceptance is closely related to how well an individual tolerates background noise, regardless of improved speech understanding in background noise. The acceptable noise level (ANL) test was developed to quantify background noise acceptance. The ANL test measures a listener's willingness to listen to speech in noise rather than their ability to understand speech in noise, and is clinically valuable as a predictor of hearing aid success. PURPOSE: Noise acceptance is thought to be mediated by central regions of the nervous system, but the underlying mechanism of noise acceptance is not well understood. Higher order central efferent mechanisms may be weaker and/or central afferent mechanisms are more active in listeners with large versus small ANLs. Noise acceptance, therefore, may not be limited to the auditory modality but observable across modalities. We designed a visual-ANL test, as a parallel of the auditory-ANL test, to examine the relations between auditory and visual noise acceptance. RESEARCH DESIGN: A correlational design. STUDY SAMPLE: Thirty-seven adults between the ages of 21 and 30 years with normal hearing participated in this study. DATA COLLECTION AND ANALYSIS: All participants completed the standard auditory-ANL task, the visual-ANL task developed for this study, reception thresholds for sentences using the hearing in noise test, and visual sentence recognition in noise using the text reception threshold test. Correlational analyses were performed to evaluate the relations between and among the ANL and perception tasks. RESULTS: Auditory- and Visual-ANLs were correlated; those who accepted more auditory noise were also those who accepted more visual noise. Auditory and visual perceptual measures were also correlated, demonstrating that both measures reflect common processes underlying the ability to recognize speech in noise. Finally, as expected, noise acceptance levels were unrelated to perception in noise across modalities. CONCLUSIONS: The results of this study support our hypothesis that noise acceptance may not be unique to the auditory modality, specifically, that the common variance shared between the two ANL tasks, may reflect a shared general perceptual or cognitive mechanism that is not specific to the auditory or visual domains. These findings also support that noise acceptance and speech recognition reflect different aspects of auditory and visual perception. Future work will relate these ANL measures with central tasks of inhibition and include hearing-impaired individuals to explore the mechanisms underlying noise acceptance.

Effects of hearing loss and spectral shaping on identification and neural response patterns of stop-consonant stimuli in young adults.

OBJECTIVES: The primary purpose of this study was to more clearly define the effects of hearing loss, separate from age, on perception, and neural response patterns of dynamic spectral cues. To do this, the study was designed to determine whether (1) hearing loss affects the neural representation and/or categorical perception of stop-consonant stimuli among young adults and (2) spectrally shaped amplification aimed at increasing the audibility of the F2 formant transition cue reduces any effects of hearing loss. It was predicted that (1) young adults with hearing loss would differ from young adults with normal hearing in their behavioral and neural responses to stop-consonant stimuli and (2) enhancing the audibility of the F2 formant transition cue relative to the rest of the stimulus would not overcome the effects of hearing loss on behavioral performance or neural response patterns. DESIGN: Behavioral identification and neural response patterns of stop-consonant stimuli varying along the /b-d-g/ place-of-articulation continuum were measured from seven young adults with mild-to-moderate hearing impairment (mean age = 21.4 yr) and compared with responses from 11 young adults with normal hearing (mean age = 27 yr). Psychometric functions and N1-P2 cortical-evoked responses were evoked by consonant-vowel (CV) stimuli without (unshaped) and with (shaped) frequency-dependent amplification that enhanced F2 relative to the rest of the stimulus. RESULTS: Behavioral identification and neural response patterns of stop-consonant CVs differed between the two groups. Specifically, to the unshaped stimuli, listeners with hearing loss tended to make low-frequency judgments more often (more /b/, fewer /g/) than listeners with normal hearing when categorizing along the /b-d-g/ continuum. Additionally, N1 amplitudes were larger and P2 latencies were longer to all phonemes in young adults with hearing impairment versus normal hearing. Enhancing the audibility of the F2 transition cue with spectrally shaped amplification did not alter the neural representation of the stop-consonant CVs in the young listeners with hearing loss. It did modify categorical perception such that listeners with hearing loss tended to make high-frequency judgments more often (more /g/, fewer /b/). However, shaping the stimuli did not make their psychometric functions more like those of the normal controls. Instead, young adults with hearing loss went from one extreme (low-frequency judgments with unshaped stimuli) to the other (high-frequency judgments with shaped stimuli), whereas judgments from the normal controls were more balanced. CONCLUSIONS: Hearing loss, separate from aging, seems to negatively impact identification and neural representation of time-varying spectral cues like the F2 formant transition. Enhancing the audibility of the F2 formant transition cue relative to the rest of the stimulus does not overcome the effects of hearing loss on behavioral performance or neural response patterns in young adults. Thus, the deleterious effects of hearing loss on stop-consonant perception along the place-of-articulation continuum may not only be due solely to decreased audibility but also due to improper coding by residual neurons, resulting in distortion of the time-varying spectral cue. This may explain, in part, why amplification cannot completely compensate for the effects of sensorineural hearing loss.

The Effects of Nonlinear Frequency Compression and Digital Noise Reduction on Word Recognition and Satisfaction Ratings in Noise in Adult Hearing Aid Users.

BACKGROUND: Nonlinear frequency compression (NLFC) and digital noise reduction (DNR) are hearing aid features often used simultaneously in the adult population with hearing loss. Although each feature has been studied extensively in isolation, the effects of using them in combination are unclear. PURPOSE: The effects of NLFC and DNR in noise on word recognition and satisfaction ratings in noise in adult hearing aid users were evaluated. RESEARCH DESIGN: A repeated measures design was used. STUDY SAMPLE: Two females and 13 males between the ages of 55 and 83 yr who were experienced hearing aid users participated. Thirteen were experienced with NLFC and all were experienced with DNR. Each participant was fit with Phonak Bolero Q90-P hearing instruments using their specific audiometric data and the Desired Sensation Level v5.0 (adult) fitting strategy. Fittings were verified with probe microphone measurements using speech at 65-dB sound pressure level (SPL). NLFC verification was performed using the Protocol for the Provision of Amplification, Version 2014.01. DATA COLLECTION AND ANALYSIS: All testing was conducted in a double-walled sound booth. Four hearing aid conditions were used for all testing: Baseline (NLFC off, DNR off), NLFC only, DNR only, and Combination (NLFC on, DNR on). A modified version of the Pascoe's High-Frequency Word List was presented at 65-dB SPL with speech spectrum noise at 6-dB signal-to-noise ratio (SNR) and 1-dB SNR for each hearing aid condition. Listener satisfaction ratings were obtained after each listening condition in terms of word comfort, word clarity, and average satisfaction. Two-way repeated measures analyses of variance were conducted to assess listener performance. Pairwise comparisons were then completed for significant main effects. RESULTS: Word recognition results indicated a significant SNR effect only (6 dB SNR > 1 dB SNR). Satisfaction ratings results indicated a significant SNR and hearing aid condition effect for clarity, comfort, and average satisfaction. Clarity ratings were significantly higher for DNR and Combination than NLFC. Comfort ratings were significantly higher for DNR than NLFC. Average satisfaction was significantly higher for DNR and Combination than for NLFC. Also, average ratings were significantly higher for Combination than Baseline. CONCLUSIONS: Activating NLFC or DNR in isolation or in combination did not significantly impact word recognition in noise. Activating NLFC in isolation reduced satisfaction ratings relative to the DNR or Combination conditions. The isolated use of DNR significantly improved all satisfaction ratings when compared with the isolated use of NLFC. These findings suggest NLFC should not be used in isolation and should be coupled with DNR for best results. Future research should include a field trial as this was a limitation of the study.

The Effects of Extended Input Dynamic Range on Laboratory and Field-Trial Evaluations in Adult Hearing Aid Users.

BACKGROUND: Digital hearing aids using a 16-bit analog-to-digital converter (ADC) provide a 96-dB input dynamic range. The level at which the ADC peak clips and distorts input signals ranges between 95 and 105 dB SPL. Recent research evaluated the effect of extending the input dynamic range in a commercially available hearing aid. Although the results were promising, several limitations were noted by the authors. Laboratory testing was conducted using recordings from hearing aids set for a flat 50-dB loss; however, field testing was conducted with hearing aids fitted for their hearing loss. In addition, participants rarely encountered input levels of sufficient intensity to adequately test the feature and were unable to directly compare aids with and without extended input dynamic range (EIDR) under identical conditions. PURPOSE: The effects of EIDR under realistic and repeatable test conditions both within and outside the laboratory setting were evaluated. RESEARCH DESIGN: A repeated measures design was used. The experiment was single-blinded. STUDY SAMPLE: Twenty adults (14 males and six females) between the ages of 30 and 71 years (average age 62 years) who were experienced hearing aid users participated. DATA COLLECTION AND ANALYSIS: Each participant was fit with Oticon Opn hearing instruments binaurally using the National Acoustics Laboratory-Nonlinear 1 fitting strategy. Participants completed a two-week trial period using hearing aids with EIDR and a two-week trial period without EIDR. The initial EIDR condition trial period was counterbalanced. After each trial, laboratory evaluations were obtained at 85 dBC using the Connected Speech Test, the Hearing in Noise Test, and the acceptable noise level (ANL). Satisfaction ratings were conducted at 85 dBC using speech in quiet and in noise as well as music. Field-trial evaluations were obtained using the abbreviated profile of hearing aid benefit (APHAB). Satisfaction ratings were also conducted in the field at 85 dBC using speech and music. After the study, each participant indicated which trial period they preferred overall. Repeated measures analysis of variances were conducted to assess listener performance. Pairwise comparisons were then completed for significant main effects. RESULTS: In the laboratory, results did not reveal significant differences between EIDR conditions on any speech perception in noise test or any satisfaction rating measurement. In the field, results did not reveal significant differences between the EIDR conditions on the APHAB or on any of the satisfaction rating measurements. Nine participants (45%) preferred the EIDR condition. Fifteen participants (75%) indicated that speech clarity was the most important factor in determining the overall preference. Sixteen participants (80%) preferred the EIDR condition that resulted in the lower ANL. CONCLUSIONS: The use of EIDR in hearing aids within and outside the laboratory under realistic and repeatable test conditions did not positively or negatively impact performance or preference. Results disagreed with previous findings obtained in the laboratory that suggested EIDR improved performance; however, results agreed with previous findings obtained in the field. Future research may consider the effect of hearing aid experience, input level, and noise acceptance on potential benefit with EIDR.

Effect of Intensity Level and Speech Stimulus Type on the Vestibulo-Ocular Reflex.

BACKGROUND: Accurate vestibulo-ocular reflex (VOR) measurement requires control of extravestibular suppressive factors such as visual fixation. Although visual fixation is the dominant suppressor and has been extensively studied, the mechanisms underlying suppression from nonvisual factors of attention and auditory stimulation are less clear. It has been postulated that the nonvisual suppression of the VOR is the result of one of two mechanisms: (1) activation of auditory reception areas excites efferent pathways to the vestibular nuclei, thus inhibiting the VOR or (2) cortical modulation of the VOR results from directed attention, which implies a nonmodality-specific process. PURPOSE: The purpose of this research was to determine if the VOR is affected by the intensity level and/or type of speech stimulus. RESEARCH DESIGN: A repeated measures design was used. The experiment was single-blinded. STUDY SAMPLE: Participants included 17 adults (14 females, three males) between the ages of 18-34 years who reported normal oculomotor, vestibular, neurological, and musculoskeletal function. DATA COLLECTION AND ANALYSIS: Each participant underwent slow harmonic acceleration testing in a rotational chair. VOR gain was assessed at 0.02, 0.08, and 0.32 Hz in quiet (baseline). VOR gain was also assessed at each frequency while a forward running speech stimulus (attentional) or a backward running speech stimulus (nonattentional) was presented binaurally via insert earphones at 42, 62, and 82 dBA. The order of the conditions was randomized across participants. VOR difference gain was calculated as VOR gain in the auditory condition minus baseline VOR gain. To evaluate auditory efferent function, the medial olivocochlear reflex (MOCR) was assayed using transient-evoked otoacoustic emissions (right ear) measured in the presence and absence of broadband noise (left ear). Contralateral acoustic reflex thresholds were also assessed using a broadband noise elicitor. A three-way repeated measures analysis of variance was conducted to evaluate the effect of frequency, intensity level, and speech type on VOR difference gain. Correlations were conducted to determine if difference gain was related to the strength of the MOCR and/or to the acoustic reflex threshold. RESULTS: The analysis of variance indicated that VOR difference gain was not significantly affected by the intensity level or the type of speech stimulus. Correlations indicated VOR difference gain was not significantly related to the strength of the MOCR or the acoustic reflex threshold. CONCLUSIONS: The results were in contrast to previous research examining the effect of auditory stimulation on VOR gain as auditory stimulation did not produce VOR suppression or enhancement for most of the participants. Methodological differences between the studies may explain the discrepant results. The removal of an acoustic target from space to attend to may have prevented suppression or enhancement of the VOR. Findings support the hypothesis that VOR gain may be affected by cortical modulation through directed attention rather than due to activation of efferent pathways to the vestibular nuclei.