Word Identification With Temporally Interleaved Competing Sounds by Younger and Older Adult Listeners.

OBJECTIVES: The purpose of this experiment was to contribute to our understanding of the nature of age-related changes in competing speech perception using a temporally interleaved task. DESIGN: Younger and older adults (n = 16/group) participated in this study. The target was a five-word sentence. The masker was one of the following: another five-word sentence; five brief samples of modulated noise; or five brief samples of environmental sounds. The stimuli were presented in a temporally interleaved manner, where the target and masker alternated in time, always beginning with the target. Word order was manipulated in the target (and in the masker during trials with interleaved words) to compare performance when the five words in each stream did versus did not create a syntactically correct sentence. Talker voice consistency also was examined by contrasting performance when each word in the target was spoken by the same talker or by different talkers; a similar manipulation was used for the masker when it consisted of words. Participants were instructed to repeat back the target words and ignore the intervening words or sounds. Participants also completed a subset of tests from the NIH Cognitive Toolbox. RESULTS: Performance on this interleaved task was significantly associated with listener age and with a metric of cognitive flexibility, but it was not related to the degree of high-frequency hearing loss. Younger adults' performance on this task was better than that of older adults, especially for words located toward the end of the sentence. Both groups of participants were able to take advantage of correct word order in the target, and both were negatively affected, to a modest extent, when the masker words were in correct syntactic order. The two groups did not differ in how phonetic similarity between target and masker words influenced performance, and interleaved environmental sounds or noise had only a minimal effect for all listeners. The most robust difference between listener groups was found for the use of voice consistency: older adults, as compared with younger adults, were less able to take advantage of a consistent target talker within a trial. CONCLUSIONS: Younger adults outperformed older adults when masker words were interleaved with target words. Results suggest that this difference was unlikely to be related to energetic masking and/or peripheral hearing loss. Rather, age-related changes in cognitive flexibility and problems encoding voice information appeared to underlie group differences. These results support the contention that, in real-life competing speech situations that produce both energetic and informational masking, older adults' problems are due to both peripheral and nonperipheral changes.

Speech-in-Noise and Quality-of-Life Measures in School-Aged Children With Normal Hearing and With Unilateral Hearing Loss.

OBJECTIVES: (1) Measure sentence recognition in co-located and spatially separated target and masker configurations in school-aged children with unilateral hearing loss (UHL) and with normal hearing (NH). (2) Compare self-reported hearing-related quality-of-life (QoL) scores in school-aged children with UHL and NH. DESIGN: Listeners were school-aged children (6 to 12 yrs) with permanent UHL (n = 41) or NH (n = 35) and adults with NH (n = 23). Sentence reception thresholds (SRTs) were measured using Hearing In Noise Test-Children sentences in quiet and in the presence of 2-talker child babble or a speech-shaped noise masker in target/masker spatial configurations: 0/0, 0/-60, 0/+60, or 0/±60 degrees azimuth. Maskers were presented at a fixed level of 55 dBA, while the level of the target sentences varied adaptively to estimate the SRT. Hearing-related QoL was measured using the Hearing Environments and Reflection on Quality of Life (HEAR-QL-26) questionnaire for child subjects. RESULTS: As a group, subjects with unaided UHL had higher (poorer) SRTs than age-matched peers with NH in all listening conditions. Effects of age, masker type, and spatial configuration of target and masker signals were found. Spatial release from masking was significantly reduced in conditions where the masker was directed toward UHL subjects' normal-hearing ear. Hearing-related QoL scores were significantly poorer in subjects with UHL compared to those with NH. Degree of UHL, as measured by four-frequency pure-tone average, was significantly correlated with SRTs only in the two conditions where the masker was directed towards subjects' normal-hearing ear, although the unaided Speech Intelligibility Index at 65 dB SPL was significantly correlated with SRTs in four conditions, some of which directed the masker to the impaired ear or both ears. Neither pure-tone average nor unaided Speech Intelligibility Index was correlated with QoL scores. CONCLUSIONS: As a group, school-aged children with UHL showed substantial reductions in masked speech perception and hearing-related QoL, irrespective of sex, laterality of hearing loss, and degree of hearing loss. While some children demonstrated normal or near-normal performance in certain listening conditions, a disproportionate number of thresholds fell in the poorest decile of the NH data. These findings add to the growing literature challenging the past assumption that one ear is "good enough."

Characteristics of noise exposure during solitary trumpet playing: immediate impact on distortion-product otoacoustic emissions and long-term implications for hearing.

OBJECTIVES: The objectives of this investigation were to quantify noise exposures generated during a 1 hr trumpet practice session and to determine whether distortion-product otoacoustic emissions (DPOAEs) are affected by such exposure, to describe the distribution of intensity levels and temporal characteristics of noise produced by trumpet practice, and to determine the effect of earplug use on generated noise levels and DPOAEs. DESIGN: In experiment 1, eight college-age trumpeters underwent an otoscopic inspection, tympanometry, and pure-tone threshold testing. Using a Grason-Stadler 60 DPOAE system, DPOAEs were recorded just before a 1 hr practice session, at 2 min after the practice session, 4 min after the session, and at 4 min intervals thereafter for a total period of 1 hr. A Hewlett-Packard 3569A Real-Time Frequency Analyzer was used to integrate noise levels to assess the overall level of exposure averaged over the course of the hour. In experiment 2, seven different trumpeters participated in two data-collection sessions. The main difference between the sessions was that subjects wore E.A.R. earplugs during session 2. All other design parameters were similar to those of experiment 1. RESULTS: Noise levels generated during the practice sessions resulted in average Leqs of 95.96, 96.6, and 96.43 dB SPL. A sound-distribution analysis revealed that noise levels exceeded 85 dB for an average of 43.73 min per session. Mean Leq values did not change when subjects wore earplugs (96.6 dB SPL versus 96.43 dB SPL.) Predictions (ISO 1999) of the increased risk of hearing loss that trumpeters would experience at 40, 50, and 60 years of age were made and indicated that trumpeters are at a significantly increased risk of hearing loss over that contributable to age alone. This increased risk is apparent with as little as 1 hr of exposure per day and suggests that 60-year-old male and female musicians exposed to trumpet noise for 4 hr per day for 40 years would be 85% and 300%, respectively, more likely to have hearing loss than their peers with negative noise exposure histories. Statistically significant decreases in DPOAE amplitudes from the prenoise exposure collection point to the 2 min post exposure point were observed only when subjects were not wearing earplugs during their practice session. Recovery of DPOAEs to baseline level varied in form for four test frequencies. CONCLUSION: During solitary play, trumpeters generate noise levels that temporarily decrease DPOAE amplitudes and that by themselves have the potential to result in permanent noise-induced hearing loss. Trumpeters who practice/perform over a period of years should be concerned about the implications of their craft on their hearing and should be offered personalized hearing conservation programs. The use of earplugs offers a practical and cost-effective means of hearing protection and, for this group of trumpeters, did not lead to an increase in playing level.

Auditory Comprehension in School-Aged Children With Normal Hearing and With Unilateral Hearing Loss.

Purpose The purpose of this study was to measure auditory comprehension performance in school-aged children with unilateral hearing loss (UHL) and with normal hearing (NH) in quiet and in the presence of child-produced two-talker babble (TTB). Method Listeners were school-aged children (7-12 years) with permanent UHL (n = 25) or NH (n = 14). Comprehension of three short stories taken from the Test of Narrative Language (Gillam & Pearson, 2004) was measured in quiet and in the presence of TTB at two signal-to-noise ratios (SNRs): (a) +6 dB and (b) the individualized SNR required to achieve 50% sentence understanding in the presence of the same TTB masker in a prior study (Griffin, Poissant, & Freyman, 2019). Target/masker spatial configuration was 0°/±60° azimuth. Results As a group, subjects with UHL demonstrated auditory comprehension abilities in favorable listening environments (i.e., quiet, +6 dB SNR) that were statistically equivalent to the NH group. However, in the most challenging listening condition (individualized SNR), many subjects with UHL demonstrated poorer comprehension performance than their age-matched peers with NH. Comprehension abilities were not associated with degree of UHL, unaided speech intelligibility index at 65 dB SPL in the impaired ear, side of UHL, or sex. Conclusions As a group, children with UHL demonstrated deficits in auditory comprehension compared to age-matched peers with NH in challenging listening environments. Findings highlight the importance of ensuring good SNRs for children with UHL.

Effects of source-to-listener distance and masking on perception of cochlear implant processed speech in reverberant rooms.

Two experiments examined the effects of source-to-listener distance (SLD) on sentence recognition in simulations of cochlear implant usage in noisy, reverberant rooms. Experiment 1 tested sentence recognition for three locations in the reverberant field of a small classroom (volume=79.2 m(3)). Subjects listened to sentences mixed with speech-spectrum noise that were processed with simulated reverberation followed by either vocoding (6, 12, or 24 spectral channels) or no further processing. Results indicated that changes in SLD within a small room produced only minor changes in recognition performance, a finding likely related to the listener remaining in the reverberant field. Experiment 2 tested sentence recognition for a simulated six-channel implant in a larger classroom (volume=175.9 m(3)) with varying levels of reverberation that could place the three listening locations in either the direct or reverberant field of the room. Results indicated that reducing SLD did improve performance, particularly when direct sound dominated the signal, but did not completely eliminate the effects of reverberation. Scores for both experiments were predicted accurately from speech transmission index values that modeled the effects of SLD, reverberation, and noise in terms of their effects on modulations of the speech envelope. Such models may prove to be a useful predictive tool for evaluating the quality of listening environments for cochlear implant users.

Speech intelligibility in cochlear implant simulations: Effects of carrier type, interfering noise, and subject experience.

Channel vocoders using either tone or band-limited noise carriers have been used in experiments to simulate cochlear implant processing in normal-hearing listeners. Previous results from these experiments have suggested that the two vocoder types produce speech of nearly equal intelligibility in quiet conditions. The purpose of this study was to further compare the performance of tone and noise-band vocoders in both quiet and noisy listening conditions. In each of four experiments, normal-hearing subjects were better able to identify tone-vocoded sentences and vowel-consonant-vowel syllables than noise-vocoded sentences and syllables, both in quiet and in the presence of either speech-spectrum noise or two-talker babble. An analysis of consonant confusions for listening in both quiet and speech-spectrum noise revealed significantly different error patterns that were related to each vocoder's ability to produce tone or noise output that accurately reflected the consonant's manner of articulation. Subject experience was also shown to influence intelligibility. Simulations using a computational model of modulation detection suggest that the noise vocoder's disadvantage is in part due to the intrinsic temporal fluctuations of its carriers, which can interfere with temporal fluctuations that convey speech recognition cues.

Acoustic and perceptual appraisal of speech production in pediatric cochlear implant users.

OBJECTIVE: The purpose of the present study was to examine the relationship between objectively measurable acoustic changes in speech production and subjective speech production accuracy and perceived intelligibility immediately following a disruption in auditory feedback normally provided to subjects from a cochlear implant. METHODS: Six children with profound sensorineural hearing loss participated in the study. Their task was to produce speech samples in two conditions: (1) with auditory feedback from their cochlear implants, and (2) without auditory feedback from their cochlear implants. Samples were subjected to both objective and subjective analyses. Objectively, measures were made of duration, fundamental frequency, and the first and second formants of the vowels. Subjectively, two groups of listeners, one familiar with the speech of children with hearing loss and the other unfamiliar, transcribed the productions and provided ratings of intelligibility. RESULTS: All the children in this study exhibited significant differences from the cochlear implant-on to the cochlear implant-off condition, although these changes were not always in the predicted direction, nor were they always perceptually salient. CONCLUSIONS: Consistent with previous studies, children in this investigation demonstrated variable acoustic voice and speech changes following deactivation of their cochlear implant device. Few of these acoustic changes affected speech intelligibility. The results of this study overall suggest that during the initial years following implantation children who are deaf rely to some extent on the auditory feedback provided by a cochlear implant to control and modify F0, duration, and vowel formant production.

Cochlear implantation in a patient with neurofibromatosis type 1 and profound hearing loss: evidence to support a cochlear site of lesion.

OBJECTIVE: To determine the efficacy of cochlear implantation in an individual with neurofibromatosis type 1 and profound hearing loss and to determine, to the extent possible in a living subject, the site of lesion of the hearing loss in an individual with neurofibromatosis type 1. STUDY DESIGN: Postoperative assessment of an adult male with neurofibromatosis type 1. SETTING: The study was completed in the Departments of Otolaryngology and Audiology, University of Massachusetts Medical Center, Massachusetts. PATIENTS: One adult male with neurofibromatosis type 1 and bilateral, chiefly profound, sensorineural hearing loss. INTERVENTIONS: The subject underwent cochlear implantation as treatment of bilateral, chiefly profound sensorineural hearing loss. MAIN OUTCOME MEASURES: Outcome measures include results of electrical auditory brainstem response testing, electrical compound action potential measures, and speech recognition scores. RESULTS: Results of testing revealed expected latencies of waves II, III, and V of the electrical auditory brainstem response, measurable compound action potentials across virtually the entire length of the electrode array, and high levels of open-set, auditory-only speech understanding. CONCLUSIONS: This is the first case report describing the outcome of cochlear implantation in a patient with neurofibromatosis type 1. Composite test results support the absence of VIIIth nerve degeneration or other anomalies, indicating a cochlear site of lesion for the hearing loss in this patient. Based on the results of this investigation, standard cochlear implantation should be considered a viable option and the first line of therapy for the treatment of bilateral, severe to profound sensorineural hearing loss in patients with neurofibromatosis type 1 and normal, VIIIth nerve radiographic findings.

Determining cochlear implant users' true noise tolerance: use of speech reception threshold in noise testing.

OBJECTIVE: The speech perception abilities of cochlear implant (CI) recipients have significantly improved over the past decade. At the same time, clinical test batteries to measure their performance in noise remain mostly unchanged, resulting in ceiling-level performance for the most successful recipients. The goal of this study is to determine the true noise tolerance abilities of CI recipients using adaptive speech reception threshold (SRT) in noise testing. STUDY DESIGN: Prospective clinical study. SETTING: Tertiary care hospital; CI program. PATIENTS: Ten CI users, either unilateral or bilateral, with HINT scores that equaled or exceeded 80% when administered with a fixed +10 dB signal-to-noise (SNR) ratio (i.e., HINT(+10dB)). INTERVENTION: The HINT with adaptive SNR levels and QuickSIN test were administered to measure noise tolerance at speech thresholds where 50% of the stimuli were correctly perceived. MAIN OUTCOME MEASURE(S): SRTs were measured for both the adaptive SNR HINT (i.e., HINT(50%)) and the QuickSIN test. These SRTs were compared with the fixed noise level HINT(+10dB) scores as well as to CNC monosyllable word perception scores. RESULTS: Despite small variance in performance levels on the HINT(+10dB), results of the HINT(50%) (∼16 dB range) and QuickSIN (∼12 dB range) tests demonstrate significant differences in noise tolerance levels among these CI recipients. CONCLUSION: For excellent CI users, use of adaptive speech threshold tests in noise better defines a user's actual ability to perceive speech than do fixed SNR level tests. SRT-in-noise tests have the advantage of being quick to administer, and the same stimuli can be used over a very wide range of performance levels. The use of adaptive SRT-in-noise tests should be considered a viable and valuable replacement of fixed SNR tests in the CI clinical test battery.

A predictive model of cochlear implant performance in postlingually deafened adults.

OBJECTIVE: To develop a predictive model of cochlear implant (CI) performance in postlingually deafened adults that includes contemporary speech perception testing and the hearing history of both ears. STUDY DESIGN: Retrospective clinical study. Multivariate predictors of speech perception after CI surgery included duration of any degree of hearing loss (HL), duration of severe-to-profound HL, age at implantation, and preoperative Hearing in Noise Test (HINT) sentences in quiet and HINT sentences in noise scores. Consonant-nucleus-consonant (CNC) scores served as the dependent variable. To develop the model, we performed a stepwise multiple regression analysis. SETTING: Tertiary referral center. PATIENTS: Adult patients with postlingual severe-to-profound HL who received a multichannel CI. Mean follow-up was 28 months. Fifty-five patients were included in the initial bivariate analysis. INTERVENTION(S): Multichannel cochlear implantation. MAIN OUTCOME MEASURES(S): Predicted and measured postoperative CNC scores. RESULTS: The regression analysis resulted in a model that accounted for 60% of the variance in postoperative CNC scores. The formula is (pred)CNC score = 76.05 + (-0.08 x DurHL(CI ear)) + (0.38 x pre-HINT sentences in quiet) + (0.04 x long sev-prof HL(either ear)). Duration of HL was in months. The mean difference between predicted and measured postoperative CNC scores was 1.7 percentage points (SD, 16.3). CONCLUSION: The University of Massachusetts CI formula uses HINT sentence scores and the hearing history of both ears to predict the variance in postoperative monosyllabic word scores. This model compares favorably with previous studies that relied on Central Institute for the Deaf sentence scores and uses patient data collected by most centers in the United States.

Impact of cochlear implantation on speech understanding, depression, and loneliness in the elderly.

OBJECTIVE: To compare speech understanding ability, the level of depression, and the degree of loneliness experienced by elderly cochlear implant (CI) users (>or= 70 years), adult CI users (or= 70 years). DESIGN: Clinical study. SETTING: Tertiary academic neuro-otologic and audiologic centre. METHODS: Three groups of patients were enrolled: (1) nine unilateral CI users 70 years or older at the time of implantation (mean 77.7 years), (2) eight unilateral CI users 60 years or younger at the time of implantation (mean 51.1 years), and (3) nine bilateral HA users 70 years or older (mean 77.5 years). Subjects underwent speech perception testing and completed two scales regarding their perceived levels of depression (pre-/post-CI) and feelings of loneliness (pre-/post-CI). MAIN OUTCOME MEASURE: Speech understanding scores in quiet and in noise and quality of life indicators (UCLA Loneliness Questionnaire, Geriatric Depression Screening Scale). RESULTS: There were no perioperative complications. No significant differences in speech understanding ability in quiet or in noise between elderly and younger CI patients were observed (p < .05). Cochlear implantation decreased perceived depression in elderly recipients and loneliness in both elderly and younger recipients. Finally, elderly CI users were no more depressed or lonely than their age-matched peers with mild-to-moderate hearing loss who use HAs. CONCLUSIONS: Cochlear implantation in elderly patients results in speech perception abilities comparable to those of younger CI recipients, as well as measurable improvements in depression and loneliness.

Effects of reverberation and masking on speech intelligibility in cochlear implant simulations.

Two experiments investigated the impact of reverberation and masking on speech understanding using cochlear implant (CI) simulations. Experiment 1 tested sentence recognition in quiet. Stimuli were processed with reverberation simulation (T=0.425, 0.266, 0.152, and 0.0 s) and then either processed with vocoding (6, 12, or 24 channels) or were subjected to no further processing. Reverberation alone had only a small impact on perception when as few as 12 channels of information were available. However, when the processing was limited to 6 channels, perception was extremely vulnerable to the effects of reverberation. In experiment 2, subjects listened to reverberated sentences, through 6- and 12-channel processors, in the presence of either speech-spectrum noise (SSN) or two-talker babble (TTB) at various target-to-masker ratios. The combined impact of reverberation and masking was profound, although there was no interaction between the two effects. This differs from results obtained in subjects listening to unprocessed speech where interactions between reverberation and masking have been shown to exist. A speech transmission index (STI) analysis indicated a reasonably good prediction of speech recognition performance. Unlike previous investigations, the SSN and TTB maskers produced equivalent results, raising questions about the role of informational masking in CI processed speech.