Auditory Rehabilitation Effects on Speech Lateralization in Hearing-impaired Listeners

Objective—Previous studies reported that the consequences of auditory rehabilitation were lateralized, with the right ear (RE) showing more improvement than the left ear (LE) over the time course of hearing aid (HA) use in elderly patients with symmetrical presbyacusis. It has been suggested that this asymmetry is linked to a change in speech lateralization. The aim of this study was to explore the consequences of HA use on interaural asymmetry in symmetrical sensorineural hearing impairment patients before and 4 months after binaural HA fitting. Material and Methods—Two types of perceptual task were chosen in order to measure speech lateralization: two dichotic listening tasks; and an identification task for a voice onset time continuum. Seven elderly, right-handed patients suffering from symmetrical presbyacusis were selected and tested before HA fitting and 4 months after. All measurements were made without the use of the HA, and the listeners were all first-time HA wearers. Results—Dichotic listening scores for words improved significantly over the course of HA use. Moreover, the dichotic listening task for syllables revealed an increase in auditory asymmetry after 4 months of HA use. Concerning the identification task, a significant difference between ears was found, with only the RE showing significant improvement with HA use. Conclusion—These results suggest that auditory rehabilitation is lateralized, with greater change as a result of HA use occurring in the RE than the LE in right-handed patients.     

Factors affecting the Mandarin dichotic digits test

Abstract

Objective: Data with regard to the Mandarin dichotic digits test (DDT) are limited, with conflicting results reported between the Mandarin and English DDTs. The current study examined factors that might affect the performance in the Mandarin DDT.

Design: The digits were arranged in 3 sets of 20 dichotic pairs; each set comprised 2, 3 or 4 digits in a pair.

Study sample: Forty-one young, native Mandarin speakers with normal hearing were tested; 30 of them were right-handed and 11 left-handed. Six participants repeated the test.

Results: The prevalence of ceiling effect in recognition score decreased systematically as the digit-pair length increased. At digit sets of 3-pair and 4-pair, the right-handed group showed a significant higher recognition score at right ear than left ear, while the left-handed group reversed the performance. The score difference between ears is significantly different between the right- and left-handed groups. The retest of the Mandarin DDT was reliable.

Conclusions: For the right-handed group, a right-ear advantage can exist in the Mandarin DDT at a longer digit-pair length, similar to what was reported in the English DDT. Moreover, for the left-handed group, the attended right hemisphere in processing the tonal digits can result in a left-ear advantage.     

Threshold changes of ABR results in toddlers and children

IntroductionAuditory brainstem response (ABR) is a clinically established method to identify the hearing threshold in young children and is regularly performed after hearing screening has failed. Some studies have shown that, after the first diagnosis of hearing impairment in ABR, further development takes place in a spectrum between progression of hearing loss and, surprisingly, hearing improvement.ObjectiveThe aim of this study is to evaluate changes over time of auditory thresholds measured by ABR among young children.Material and MethodsFor this retrospective study, 459 auditory brainstem measurements were performed and analyzed between 2010 and 2014. Hearing loss was detected and assessed according to national guidelines. 104 right ears and 101 left ears of 116 children aged between 0 and 3 years with multiple ABR measurements were included. The auditory threshold was identified using click and/or NB-chirp-stimuli in natural sleep or in general anesthesia. The frequency of differences of at least more than 10 dB between the measurements was identified.ResultsIn 37 (35%) measurements of right ears and 38 (38%) of left ears there was an improvement of the auditory threshold of more than 10 dB; in 27 of those measurements more than 20 dB improvement was found. Deterioration was seen in 12% of the right ears and 10% of the left ears. Only half of the children had stable hearing thresholds in repeated measurements. The time between the measurements was on average 5 months (0 to 31 months).ConclusionHearing threshold changes are often seen in repeated ABR measurements. Therefore multiple measurements are necessary when ABR yields abnormal. Hearing threshold changes should be taken into account for hearing aid provision.     

Dichotic word recognition in young and older adults

Dichotic word recognition was evaluated in free-recall, directed-attention right, and directed-attention left response conditions. All participants were right-handed and included a group of young adults with normal hearing and two groups of older adults with sensorineural hearing loss. Dichotic word recognition performance was best for young adults and decreased for each older group. A right-ear advantage (REA) was observed for all groups. REAs observed in the older groups were larger than those for the young adults, resulting from a greater deficit in dichotic word recognition performance for words presented to the left ear. A subset of older adults exhibited few to no responses (< or = 3/100) for the left ear for all response conditions, which may relate to a compromise in auditory processing. The results support an age-related disadvantage in recognition performance for dichotic stimuli presented to the left ear not entirely accounted for by differences in hearing sensitivity between subject groups.     

Development,and validation of non-speech dichotic listening test

Background: Classic dichotic listening tests using speech stimuli result in right ear advantage, due to the dominant crossed pathway for speech and language. It is presumed that similar crossed dominance could exist for non-speech stimuli too. Hence, this is an attempt to develop and validate the dichotic nonspeech test using environmental stimuli and explore the effect of focused attention on this test.Materials and method: Three lists of dichotic stimuli were created using these sounds with fi...     

Amplitude and phase-shift effects on dichotic listening performance

Abstract

Objective: Previous dichotic listening (DL) studies have shown that interaural amplitude or phase shifts have powerful effects on dichotic ear advantage. However, it is not known how these two factors interact. The present study aims to explore this interaction when amplitude (intensity) and phase (time) shifts occur simultaneously. Design: Participants listened to dichotically presented pairs of consonant-vowel syllables (216 trials) under nine different experimental conditions, systematically varying amplitude (+9 dB) and phase (+35 ms) shifts. Participants reported which syllable they perceived on each trial. Study sample: Thirty-two healthy adults. Results: The results showed an expected right ear advantage (REA) in the baseline (nosound manipulation) condition. While amplitude shifts favoring the right ear were found to have a greater effect on REA than phase shifts, phase shifts favoring the left ear were found to have a greater effect on left ear advantage (LEA) than amplitude shifts. Furthermore, phase shifts favoring the left ear had a greater effect on LEA than phase shifts favoring the right ear on REA. Conclusions: Present results may have consequences for the training of individuals with auditory and phonetic difficulties, e.g. auditory processing deficits or dyslexia, by aiding the design of optimal combinations of acoustic and phonetic training tools.     

Interaural asymmetries revealed by dichotic listening tests in normal and dyslexic children

Normal and dyslexic right-handed children were assessed with three dichotic listening tests, the Dichotic Digits test, the Competing Words subtest of the SCAN, and the Dichotic Consonant-Vowel test. Performance was measured as both number and percentage of correct responses in the right and left ears. Laterality was defined as a simple difference in percentage between the two ears. Differences across the tests were revealed for all children, with the greatest differences occurring for left-ear responses. Only one dichotic listening test, Competing Words from the SCAN, produced a consistent right-ear advantage across all of the children tested. Between groups of children, differences in performance and in laterality were demonstrated. Using a criterion of poorer than 76 percent correct for the left ear, the Competing Words subtest of the SCAN identified 7 of the 10 dyslexic children as abnormal, with no false alarms in the control group.     

Effects of simulated conductive hearing loss on dichotic listening performance for digits

This experiment assessed conditions under which simulated conductive hearing loss would affect performance on a digit dichotic test. Losses were simulated by insertion of EAR plugs, and each subject served as his/her own control. Performance for left ear plugged and right ear plugged conditions was compared with performance in a normal hearing condition (neither ear plugged). Conductive losses did not affect dichotic performance at test intensities 12 dB above the "knees" of monotic performance-intensity functions for the plugged ears (95% correct points) but did affect dichotic performance for some listeners at intensities that were within 8 dB of the monotic knees.     

Cortical auditory evoked responses from an implanted ear after 50 years of profound unilateral deafness

Abstract

A male with unilateral deafness in the right ear since 8 years of age developed a sudden hearing loss in the left ear at age 63. A hearing aid was fitted in the left ear with limited benefit. The right ear received a cochlear implant (CI) 20 months later. Cortical auditory evoked potentials (CAEPs) and speech recognition scores (SRS) were measured in free-field three, six and nine months after implantation with the hearing aid alone, CI alone and bimodal condition (hearing aid and CI together). Three months after implantation the cortical responses for the two ears were similar, despite more than 50 years of unilateral auditory deprivation. CAEPs measured over time show evidence of binaural interaction and improvements in SRS. Copyright © 2007 John Wiley & Sons, Ltd.     

Double challenge: cochlear implantation in the only hearing ear with progressive hearing loss following meningitis and vestibular dysfunction after implantation

ObjectiveVestibular dysfunction associated with cochlear implantation is rare. It is usually seen in patients with otosclerosis due to spread of electrical activity throughout the demineralized bone. A 17-year old female with progressive hearing loss 2 years after meningitis and vestibular dysfunction in the implanted ear is presented in this study.FindingsThe patient had mild hearing loss in the right ear and total hearing loss on the left side because of complete ossification of the cochlea following meningitis. She had to have cochlear implantation in the right ear because of progression of hearing loss. She had successful implantation but she experienced vestibular dysfunction following activation of cochlear electrodes. Closure of two electrodes caused disruption of auditory programming. Then the patient was subjected to long term vestibular rehabilitation program.ConclusionTiming for implantation before the completion of cochlear ossification is crucial not to miss the chance for hearing restoration. However, difficulties in hearing rehabilitation due to extensive ossification can be doubled by vestibular problems triggered by stimulation of the vestibular nerve by cochlear electrodes. Attempts to reduce the balance problem will complicate auditory programming. Vestibular rehabilitation for long term helps to carry on hearing progress.     

Auditory rehabilitation effects on speech lateralization in hearing-impaired listeners

OBJECTIVE: Previous studies reported that the consequences of auditory rehabilitation were lateralized, with the right ear (RE) showing more improvement than the left ear (LE) over the time course of hearing aid (HA) use in elderly patients with symmetrical presbyacusis. It has been suggested that this asymmetry is linked to a change in speech lateralization. The aim of this study was to explore the consequences of HA use on interaural asymmetry in symmetrical sensorineural hearing impairment patients before and 4 months after binaural HA fitting. MATERIAL AND METHODS: Two types of perceptual task were chosen in order to measure speech lateralization: two dichotic listening tasks; and an identification task for a voice onset time continuum. Seven elderly, right-handed patients suffering from symmetrical presbyacusis were selected and tested before HA fitting and 4 months after. All measurements were made without the use of the HA, and the listeners were all first-time HA wearers. RESULTS: Dichotic listening scores for words improved significantly over the course of HA use. Moreover, the dichotic listening task for syllables revealed an increase in auditory asymmetry after 4 months of HA use. Concerning the identification task, a significant difference between ears was found, with only the R E showing significant improvement with HA use. CONCLUSION: These results suggest that auditory rehabilitation is lateralized, with greater change as a result of HA use occurring in the RE than the LE in right-handed patients.     

Asymmetry of temporal processing in listeners with normal hearing and unilaterally deaf subjects

OBJECTIVES: In general, auditory cortex on the left side of the brain is specialized for processing of acoustic stimuli with complex temporal structure including speech, and the right hemisphere is primary for spectral processing and favors tonal stimuli and music. This asymmetry in processing is further emphasized when hemisphere-favored stimuli are presented to the contralateral ear. The purpose of the first experiment is to further investigate the properties that dictate lateralized processing of auditory stimuli by ear and the relationship between auditory task and stimulus type. Next, it is not clear what compensation may exist for the loss of function of one ear and consequently, reduced access to functions primary performed in the opposite hemisphere, in the case of early unilateral profound hearing loss. The purpose of experiment 2 is to determine if any compensation for loss of function is seen in persons with early unilateral deafness. DESIGN: Experiment 1: Gap detection thresholds were determined in 30 right-handed listeners with normal hearing using wide-band noise markers (temporally complex), 400 and 4000 Hz pure tones presented individually to the left and right ears. Experiment 2: The same procedure was administered to listeners with early-onset, severe-to-profound unilateral deafness (seven left ear deaf and five right ear deaf) in the hearing ear alone. RESULTS: A significant right ear advantage was found for gap detection threshold using noise markers and a smaller left ear advantage was found for tonal stimuli. Listeners with unilateral deafness demonstrated that the hearing ear, left or right, performed in a manner similar to listeners with normal hearing. CONCLUSIONS: Results indicate that (1) gap marker, more than task, was the salient feature in determining laterality of processing in this experiment, (2) the two ears have distinct processing capacity based on stimulus type, and (3) compensation for loss is not apparent in persons with congenital unilateral deafness.     

Differential attention effects on dichotic listening

The role of attention in the differentiation of auditory processing disorders from attention deficit disorders is gaining considerable interest in both the clinical and research arenas. It has been well established that when attention is directed to one ear or the other on traditional dichotic tests, performance can be altered. However, preliminary studies in our laboratory have shown that dichotic fusion paradigms are resistant to shifts in ear performance associated with changes in attention. The purpose of this study was to assess the performance of normal listeners on a dichotic consonant-vowel and a dichotic rhyme (fusion) test. Both test procedures were administered to 20 young adults in three different listening conditions (free recall, attention directed to the left ear, and attention directed to the right ear). Results from this study supported the hypothesis that dichotic rhyme tests are resistant to alterations in the laterality of attention and have implications for the development of test paradigms that can be used to segregate attention from pure auditory deficits in the clinical domain.     

Hearing and ear status of Pacific children aged 11 years living in New Zealand: the Pacific Islands families hearing study

Objective: This study aimed to determine the prevalence of hearing loss and ear problems in Pacific children, and investigate current and past demographic, health and social factors potentially associated with hearing and ear problems.

Design: A cross-sectional observational study design nested within a birth cohort was employed.

Study sample: Nine-hundred-twenty Pacific children aged 11?years were audiologically assessed. Using average hearing thresholds at 500, 1k and 2k Hz, 162 (18%) right and 197 (21%) left ears had ≥20?dB hearing loss. Hearing loss was mild (20–39?dB) in most cases; 2% of ears had moderate to moderate-severe (40–69?dB) hearing loss. However, only 101 (11%) children had normal peripheral hearing defined by passing hearing threshold, tympanogram and distortion product otoacoustic emission assessments. Those with confirmed middle ear disease at age 2?years had significantly increased odds of a non-Type A tympanogram (adjusted odds ratio: 2.00; 95% confidence interval: 1.56, 2.50) when re-assessed at age 11?years.

Conclusions: Hearing loss, abnormal tympanograms, and auditory processing difficulties were present in many Pacific children. Interventions are also urgently needed to mitigate the effect of the longstanding ear disease likely to be present for many Pacific children.     

Untersuchungen mit dichotischen Hörtesten bei Zweisprachigkeit

Summary Results of dichotic hearing tests in Russian and German advanced students are reported. The test material consisted of simultaneously presented German and Russian words and sentences. The results obtained showed a prepotency of the right ear in right-handed people according to hemispheric asymmetry. There is no influence on the right ear advantage, whether the presented words or sentences belong to the first or second language.     

儿童单侧听神经病附三例分析

目的 探讨儿童单侧听神经病的听力学特征。方法 对3例单侧听神经病患儿进行纯音听阈(PTT)、声反射(AR)、听性脑干反应(ABR)和畸变产物耳声发射(DPOAE)检查，并对其结果进行综合分析。结果 3例患儿的PTT均呈1侧耳听力正常，另1侧耳听力丧失。健耳的同侧和交叉AR能引出，患耳的同侧和交叉AR未能引出。健耳的ABR各波潜伏期正常，患耳的ABR各波未能引出。双耳DPOAE各频率反应幅值正常。结论：DPOAE正常或基本正常，PTT、AR和ABR异常是听神经病的重要特征。单侧听神经病的听力学特征与双侧听神经病基本一致。对儿童表现为单侧感音神经性聋者宜进行系统的听力学检查，以期作出正确的诊断。     

Assessment of two central auditory tests in elderly patients without hearing complaints

Speech understanding disorders in the elderly may be due to peripheral or central auditory dysfunctions. Asymmetry of results in dichotic testing increases with age, and may reflect on a lack of inter-hemisphere transmission and cognitive decline.Aim: To investigate auditory processing of aged people with no hearing complaints.Study design: clinical prospective.Materials and Methods: Twenty-two voluntary individuals, aged between 55 and 75 years, were evaluated. They reported no hearing complaints and had maximal auditory thresholds of 40 dB HL until 4 KHz, 80% of minimal speech recognition scores and peripheral symmetry between the ears. We used two kinds of tests: speech in noise and dichotic alternated dissyllables (SSW). Results were compared between males and females, right and left ears and between age groups.Results: There were no significant differences between genders, in both tests. Their Left ears showed worse results, in the competitive condition of SSW. Individuals aged 65 or older had poorer performances than those aged 55 to 64.Conclusion: Central auditory tests showed worse performance with aging. The employment of a dichotic test in the auditory evaluation setting in the elderly may help in the early identification of degenerative processes, which are common among these patients.     

Adverse effects of pesticides on central auditory functions in tobacco growers

Objective: To investigate the effects of exposure to pesticides on the central auditory functions (CAF) of Brazilian tobacco growers. Design: This was a cross-sectional study carried out between 2010 and 2012. Participants were evaluated with two behavioural procedures to investigate CAF, the random gap detection test (RGDT) and the dichotic digit test in Portuguese (DDT). Study sample: A total of 22 growers exposed to pesticides (study group) and 21 subjects who were not exposed to pesticides (control group) were selected. Results: No significant differences between groups were observed for pure-tone thresholds. A significant association between pesticide exposure and the results for RGDT and DDT was found. Significant differences between pesticide-exposed and nonexposed subjects were found for RGDT frequency average and DDT binaural average, when including age and hearing level as covariates. Age was significantly associated with RGDT frequency average, DDT left ear score, DDT binaural average and DDT right ear advantage. Hearing levels were not significantly associated with any of the test scores. The relative risk of failing the DDT and RGDT for the study group was 1.88 (95% CI:?1.10–3.20) and 1.74 (95% CI:?1.06–2.86), respectively, as compared with the control group. Conclusions: The results showed that tobacco growers exposed to pesticides exhibited signs of central auditory dysfunction characterised by decrements in temporal processing and binaural integration processes/abilities.     

Potential benefits of across-aid communication for bilaterally aided people: Listening in a car

We explored whether transferring signals between two hearing aids could improve speech intelligibility in noise. This was evaluated using a simulated conversation in a car; speech was presented to the right ear and car noise was presented either to the right or both ears. In three cross-aid communication conditions, the noise in the right ear was scaled and subtracted from the noise in the left ear. Speech intelligibility was determined for a group of normally hearing listeners and a group with bilateral hearing loss. The hearing-impaired group had relatively higher intelligibility scores when the car noise was diotic, whereas the normal-hearing group had relatively higher intelligibility scores in the binaural (dichotic) conditions. The cross-aid conditions led to improved intelligibility compared to the reference conditions. The results indicate that the transfer of signals between hearing aids may be of benefit when listening to speech in a car.

Sumario

Exploramos si la transferencia de señales entre dos auxiliares auditivos podría mejorar la inteligibilidad del lenguaje en ruido. Esto fue evaluado simulando una conversación en un auto; se presentó una señal de lenguaje al oído izquierdo y un ruido de automóvil en el oído derecho o en ambos. En tres condiciones de comunicación inter-audífono, el ruido en el oído derecho fue graduado y sustraído del ruido en el oído izquierdo. Se determinó la inteligibilidad del lenguaje en un grupo de sujetos normo-oyentes y en un grupo con hipoacusia bilateral. El grupo de hipoacúsicos obtuvo puntuaciones de inteligibilidad del lenguaje relativamente mayores cuando el ruido del automóvil fue diótico, mientras que el grupo de normo-oyentes obtuvo puntuaciones de inteligibilidad relativamente mayores en las condiciones binaurales (dicóticas). Las condiciones inter-audífono llevaron a una inteligibilidad mejorada, comparada con las condiciones de referencia. Los resultados indican que la transferencia de señales entre auxiliares auditivos puede ser de beneficio cuando se escucha lenguaje dentro de un auto.     

Influence of amplification on the discrimination of dichotic consonant-vowel syllables in a population with sensorineural hearing loss

This study was designed to investigate the premise that the long-term use of monaural amplification influences dichotic listening conditions in a population with sensorineural hearing losses. 30 subjects with moderate, bilateral sensorineural hearing losses and 10 normally-hearing adults were chosen for this study. 20 of the subjects with sensorineural hearing loss had worn amplification successfully for at least 1 year prior to testing. 10 of these subjects had worn amplification only on the right ear while the remaining 10 had worn amplification only on the left ear. All subjects received 60 monaural and dichotic consonant-vowel (CV) nonsense syllables presented at equal loudness levels using the most comfortable level (MCL) as the loudness criteria. While monaural scores revealed nonsignificant differences between ears for all subjects, using percentage of error, dichotic results produced a right-ear advantage for the right-ear-aided, unaided and normally-hearing subjects. A significant left-ear advantage was seen for the left-ear-aided subjects. Results of this study suggest that amplification introduces selective listening effects which alter reported dichotic test scores.